On Stability of Critical Points for the High Dimensional Onsager Functional with Maier-Saupe Potential

We study the stability of the critical points of the Onsager energy functional with Maier-Saupe interaction potential in general dimensions. We show that the stable critical points must be axisymmetric, which solves a problem proposed by [H. Wang, P. Hoffman, Commun. Math. Sci. 6 (2008), 949--974] and further conjectured by [P. Degond, A. Frouvelle, J.-G. Liu, Kinetic and Related Models, 15(2022), 417--465]. The main ingredients of the proof include a suitable decomposition of the second variation around the critical points and a detailed analysis of the relation between the intensity of interaction and the order parameter characterizing the anisotropy of the solution

Historical Trends of Cyanobacteria and their Toxins in Four Eastern Canadian Source Waters

RÉSUMÉ La mesure in situ des concentrations de cyanotoxines est laborieuse. L'étude de la dynamique des cyanobactéries et cyanotoxines est un complément important dans le domaine de l’eau. L'objectif de cette étude était de déterminer les cyanobactéries dominantes et la relation entre la biomasse et la concentration de cyanotoxines dans quatre lacs du Québec sur la base des données historiques du Ministère du Développement Durable de l’Environnement et des Parc (MDDEP). La dynamique étudiée peut être utilisée comme une base pour établir une méthode efficace pour mesurer rapidement les cyanotoxines et d'assurer une meilleure élimination des cyanotoxines dans l'eau potable. Des campagnes d'échantillonnage ont été effectuées par le MDDEP de 2000 à 2008 dans quatre lacs, Baie Missisquoi, lac Nairne, lac Brome et lac William. Cyanotoxines ont été surveillés et mesurés par des méthodes de laboratoire. Les résultats de ces observations ont permis d’effectuer une vaste surveillance des variations spatio-temporelles de l'abondance de cyanobactéries et des espèces de cyanobactéries et cyanotoxines dans les quatre lacs. L’analyse des données démontre que les concentrations de mcirocystine LR équivalent (MC-LR éq) détectées dans l’écume étaient beaucoup plus élevées que les seuils d'alerte établis par l'organisation mondiale de la santé (OMS). Il’est difficile de déterminer quelles étaient les espèces dominantes les plus abondantes dans l’eau. Cependant, les espèces dominantes ont été facilement identifiées dans l’écume. La concentration d'anatoxine détectée a toujours été faible, même inférieure à la limite de détection (LOD) (Annexe 2). Bien que l’anatoxine soit potentiellement produite par les cyanobactéries, Aphanizomenon flos-aquae et Anabaena flos-aquae étaient les espèces les plus fréquemment présentes dans les échantillons. L'abondance de cyanobactéries potentiellement MC produites dans l’écume était toujours accompagnée de forte concentration de MC-LR éq. L'analyse des données montre que la relation entre la biomasse des cyanobactéries et les concentrations de MC-LR éq n'est pas claire, cependant, quand l'eau etait dominée par des espèces spécifiques, les relations étaient beaucoup plus apparentes.----------ABSTRACT The concentration of cyanotoxins is hard to be measured in situ. The study of the dynamics of cyanobacteria and cyanotoxins is a strong complement to the drinking water scientific knowledge. The goal of this study was to identify the dominant cyanobacteria and the relationship between the biomass and the concentration of cyanotoxins in four lakes in Quebec based on the historical data obtained from the Quebec Ministry of Durable Development of Environment and Parks (MDDEP). The dynamic studied can be used as a base to establish an effective method for rapid measurement of cyanotoxins and to ensure better removal of cyanotoxins in drinking water. Sampling was conducted from 2000 to 2008 in four lakes, Missisquoi Bay, Lake Nairne, Lake Brome and Lake William. Cyanotoxins were monitored and measured by laboratory methods. The results of these monitoring showed large spatial-temporal variations of cyanobacterial abundance, cyanobacteria species, and cyanotoxins in these four lakes. The concentrations of Microcystin-LR equivalent (MC-LR eq) detected in the scums were much higher than the alert threshold established by World Health Organization (WHO). It was difficult to determine the dominant cyanobacterial species as well as the most abundant species in these waters. However, in the scum, the dominant species were easily identified. The concentration of anatoxin detected was always low even lower than the Limit of Detection (LOD) (Appendix 2), although the potentially anatoxin producing cyanobacteria, Aphanizomenon flos-aquae and Anabaena flos-aquae were the more frequent present species in samples. The abundance of potentially MC producing cyanobacteria in water always accompanied with high concentration of MC-LR eq. Data analysis demonstrates that the relationship between the biomass of cyanobacteria and the concentrations of MC-LR eq is not clear, however when water dominated by specific species, the relationships were much clearer

Antidiabetic effect of Tibetan medicine Tang-Kang-Fu-San in db/db mice via activation of PI3K/Akt and AMPK pathways

This study was to investigate the anti-diabetic effects and molecular mechanisms of Tang-Kang-Fu-San (TKFS), a traditional Tibetan medicine, in treating type 2 diabetes mellitus of spontaneous diabetic db/db mice. Firstly HPLC fingerprint analysis was performed to gain the features of the chemical compositions of TKFS. Next different doses of TKFS (0.5 g/kg, 1.0 g/kg, and 2.0 g/kg) were administrated via oral gavage to db/db mice and their controls for 4 weeks. TKFS significantly lowered hyperglycemia and ameliorated insulin resistance (IR) in db/db mice, indicated by results from multiple tests, including fasting blood glucose test, intraperitoneal insulin and glucose tolerance tests, fasting serum insulin levels and homeostasis model assessment of IR analysis as well as histology of pancreas islets. TKFS also decreased concentrations of serum triglyceride, total and low-density lipoprotein cholesterol, even though it did not change the mouse body weights. Results from western blot and immunohistochemistry analysis indicated that TKFS reversed the down-regulation of p-Akt and p-AMPK, and increased the translocation of Glucose transporter type 4 in skeletal muscles of db/db mice. In all, TKFS had promising benefits in maintaining the glucose homeostasis and reducing IR. The underlying molecular mechanisms are related to promote Akt and AMPK activation and Glucose transporter type 4 translocation in skeletal muscles. Our work showed that multicomponent Tibetan medicine TKFS acted synergistically on multiple molecular targets and signaling pathways to treat type 2 diabetes mellitus

Distraction or Connection? An Investigation of Social Media Use at Work

The use of social media in the workplace is controversial. In order to develop a good understanding of social media use at work, this study examines the effects of social media use from both positive and negative sides. Based on two-factor theory, this study proposes that social media use at work engenders distraction and perceived relatedness, which in turn influence job performance. This study further draws on resource matching theory to posit that the perceptual load of the job moderates the effects of social media use at work on distraction and perceived relatedness. A survey will be conducted to collect data and test the research hypotheses. In theoretical terms, this study is expected to contribute to information systems research by investigating both positive and negative outcomes of social media usage. In practical terms, this study sheds light on the usage and management of social media in the workplace

Investigation of the relationship between chronic stress and insulin resistance in a Chinese population

Background: Chronic stress may facilitate the development of metabolic diseases. Insulin resistance is present long before the clinical manifestations of individual metabolic abnormalities. To explore whether chronic stress is an independent risk factor of insulin resistance, we investigated the relationship between the stress system, selected parameters of energy homeostasis, and insulin resistance in a Chinese population. Methods: We recruited 766 workers employed at four companies in Beijing. The degree of insulin resistance was determined using the homeostasis model assessment of insulin resistance (HOMA-IR). The highest quartile of HOMA-IR among all study subjects was further defined as insulin resistance in our study. The short standard version of the Copenhagen Psychosocial Questionnaire (COPSOQ) was used to assess job-related psychosocial stress. Pearson\u27s correlation coefficients were calculated between cortisol level and HOMA-IR and components of metabolic syndrome, with stratification by gender. The relationship between cortisol and HOMA-IR independent of obesity was analyzed using a linear mixed model with company as a cluster unit. Results: The values of the two scales of COPSOQ, including demands at work and insecurity at work , were significantly associated with insulin resistance and cortisol concentration (P \u3c 0.05). Cortisol was significantly positively correlated with glucose, HOMA-IR, and waist circumference in males and females (P \u3c 0.05). After adjusting for potential confounders, cortisol was an independent positive predictor for HOMA-IR (P \u3c 0.05). Conclusions: These findings showed that chronic stress was associated with insulin resistance and may contribute to the development of insulin resistance

Accelerating Spatial Clustering Detection of Epidemic Disease with Graphics Processing Unit

IEEE GRSS; The Geographical Society of China<span class="MedBlackText">The statistics of disease clustering is of interest to epidemiologists. In order to detect spatial clustering of disease in all the regions of China, we adopted a likelihood ratio based method which utilizes Monte Carlo simulation and spatial exploring to analyze the real time updating data stored in database. However, large number of random tests for Monte Carlo simulation and large scale of the data set had made the speed of analysis too slow to detect and monitor potential public health hazards. Therefore, we explored to adopt graphics processing unit (GPU) and compute unified device architecture (CUDA) to accelerate the spatial exploring and analyzing process. The algorithm has been implemented efficiently on GPU and the access pattern to memory has been optimized to exploit the computing power of GPU. As a result, the GPU based spatial exploring and likelihood ratio test program performed more than forty times faster then the CPU implementation. The Monte Carlo simulation on GPU performed around thirty times faster than the counter part on CPU. By using GPU and CUDA, the usage of our application is changed from verification after the event to early warning.</span

WaterBear: Practical Asynchronous BFT Matching Security Guarantees of Partially Synchronous BFT

Asynchronous Byzantine fault-tolerant (BFT) protocols assuming no timing assumptions are inherently more robust than their partially synchronous counterparts, but typically have much weaker security guarantees. We design and implement WaterBear, a family of new and efficient asynchronous BFT protocols matching all security guarantees of partially synchronous protocols. To achieve the goal, we have developed the local coin (flipping a coin locally and independently at each replica) based BFT approach---one long deemed as being inefficient---and designed more efficient asynchronous binary agreement (ABA) protocols and their reproposable ABA (RABA) versions from local coins. Our techniques on ABA and RABA are of independent interests and also allow us to build more efficient ABA protocols from common coins (distributively generating the same random coins for all replicas), helping improve various other protocols such as distributed key generation and BFT assuming trusted setup. We implemented in total five BFT protocols in a new golang library, including four WaterBear protocols and BEAT. Via extensive evaluation, we show that our protocols are efficient under both failure-free and failure scenarios, achieving at least comparable or superior performance to BEAT with much weaker security guarantees. Specifically, the most efficient WaterBear protocol consistently outperforms BEAT in terms of all metrics. For instance, when the number of replicas is 16, the latency of our protocol is about 1/8 of that of BEAT and the throughput of our protocol is 1.23x that of BEAT. Our work pushes the boundaries of asynchronous BFT, showing the strongest security levels that we know of and high performance can co-exist

3-Phase Rectifier System with very demanding dynamic load

This paper present a distributed power architecture for aerospace application with very restrictive specifications. Additionally, the rectifier switching frequency has to be synchronized with an external frequency clock to minimize the interference of the converter harmonics with the load. In order to protect the 3 phase generator against high load steps, an intermediate bus (based in a high capacitance) to provide energy to the loads during the high load steps is included. Prototypes of the rectifier and EMI filter are built and the energy control is validated