Circles Minimize most Knot Energies

We define a new class of knot energies (known as renormalization energies) and prove that a broad class of these energies are uniquely minimized by the round circle. Most of O'Hara's knot energies belong to this class. This proves two conjectures of O'Hara and of Freedman, He, and Wang. We also find energies not minimized by a round circle. The proof is based on a theorem of G. Luko on average chord lengths of closed curves.Comment: 15 pages with 3 figures. See also http://www.math.sc.edu/~howard

A Study on anisotropy of cosmic ray distribution with a small array of water-cherenkov detectors

The study of the anisotropy of the arrival directions is an essential tool to investigate the origin and propagation of cosmic rays primaries. A simple way of recording many cosmic rays is to record coincidences between a number of detectors. We have monitored multi-TeV cosmic rays by a small array of water cherenkov detectors in Tehran(35 43 N, 51 20 E, 1200m a.s.l). More than 1.1*10^6 extensive air shower events were recorded. In addition to the Compton- Getting effect due to the motion of the earth in the Galaxy, an anisotropy has been observed which is due to a unidirectional anisotropy of cosmic ray flow along the Galactic arms.Comment: 16 pages 9 figs and one tabl

Partial synthesis of chaksine

This thesis is concerned with the preliminary studies in the synthesis of a monoterpenoid alkaloid, chaksine, Ethyl 2-methylcyclohexanone-6-carboxylate (XI) was hydroxymethylated with formaldehyde to give Ethyl 2-methyl~6-hydroxymethylcyclohexanone--6-Carboxylate (XII). Tosylation and cleavage of this product gave 2-methyl-6- carbethoxy-B-heptenoic (XIV) acid along with the diethyl ester (XIVa)» Ozonolysis of the diethyl ester yielded diethyl 2-keto-6-methyl pimelate (XV). A Wittig reaction v/ith diethyl cyanomethyl phosphonate (XVI) gave l-cyano-6~methyll- cyano-2, 6-dicarbethoxy-l-heptene (XVII). Other related studies involved: 1) Preparation of ethyl 2-methyl-6-vinylcyclohexanone-6-carboxylate (XXII), 2) A new method for preparation of 2-imidazolidones (XXIV). 3) Preparation of l-phenyl~2-aldehydo-6-methyl~l, 6-heptadiene (XXXIII) and l-n-butylthio-2-aldehydo-6-methyl-l, 6-heptadiene (XXXIX)

Yield of protein recovery and degree of hydrolysis associated protein hydrolysates from Bighead Carp (Aristichthys nobilis) by using enzymes

The present study compared the properties of Bighead carp (Aristichthys nobilis) visceral, viscera use of commercial enzymes (Alcalase, Papain, and Protamex), recovery protein and degree of hydrolysis in the various temperatures and times of hydrolysis process. According to results, increase in time and temperature in hydrolysis process, led to increase in both recovery protein and degree of hydrolysis. Maximum of these parameters were observed at 55°C and 60min. minimum of parameters were observed at 35°C and 15min. In addition, among enzymes being investigated, Alcalase had high rate of recovery protein and degree of hydrolysis in equal temperature and times different from others enzymes (Papain and Protamex). Maximum mean of recovery protein for Alcalase was %51.38±2.39 in 55°C and 60 min of hydrolysis process. Also, maximum degree of hydrolysis for Alcalaqse was more than 20% at 55°C and 60 min of hydrolysis process. In conclusion, use of Alcalase enzyme induces product protein hydrolysates from Bighead Carp (Aristichthys nobilis) viscera that have suitable quality than others enzymes (Papain, and Protamex)

Experimental Study on the Optimization of Dielectric Barrier Discharge Reactor for NOx Treatment

In this paper, a comprehensive study of a DBD reactor is conducted to investigate the optimum operating conditions of the reactor for NOx treatment. For each parameter, the objective is to find the maximum NOx removal efficiency with the minimum consumed power. Different effective parameters of the reactor i.e. electrode length and diameter, electrode and dielectric materials as well as parameters of power generator, i.e. voltage and frequency, are investigated. The results show that for this configuration, the electrode with 20 cm length and 10 mm diameter has the best performance. Aluminum as the inside electrode material and quartz as the dielectric material are selected. Furthermore, the optimum value for the pulse frequency is 16.6 kHz. For the mentioned optimum conditions, the NOx removal efficiency achieved is equal to almost 82% at the input power of 486 W. Furthermore, the highest achieved NOx removal is almost 92% at the input power of 864 W. The results of this paper can be used to reduce the energy consumption of NTP systems to acceptable levels

The effects of online social networks on the quantitative academic performance of secondary high school girls' students in Tehran

Background and Objectives: One of the important indicators in measuring the quality of education is the academic performance of students, which is important from a scientific and practical point of view. Extensive studies have been conducted worldwide on how social networks affect the quantitative academic performance of their students. Many studies on the denial of social media have concluded that these networks have a negative impact on the younger generation and students. These researchers believe that virtual social networks have an effect on students' annual grade point average, drop in academic grades, writing style and spelling, decrease in English language standards, etc., and have measured these variables separately with the use of social networks among students. At the same time, others believe that the emergence of social media has a positive trend on students' performance and their achievement of high grades. These studies have also found that these students spend most of their time doing their homework and research in this way. Therefore, in the review of previous studies, both approaches are discussed separately. The main purpose of this study is to be aware of the impact of virtual social networks on the quantitative academic performance of female high school students. Sub-objectives are to examine the extent of students 'dependence on virtual social networks and awareness of the impact of using virtual social networks on students' quantitative academic performance. Methods: In this research, a survey method has been used and the sample population includes 855 female students of high schools in Tehran. The data gathering instrument is Jeffrey Single's Social Media Dependency Questionnaire, including academic quantitative performance, social networks addiction, educational use, and grammar, writing, reading, and course questions. In this study, descriptive tests (percentage, mean, and analytical tests (chi-square, Pearson correlation coefficient and t-test) were used. Findings: The findings show that there is no relationship between the students' last year GPA and their academic quantitative performance and their use of the online social network; but there is a relationship between their GPAs and their scientific information exchange (test questions) and with their use of online social networks. The findings show that there is no relationship between last year's students' grade point average and their poor academic performance using a virtual social network. There is only a relationship between their grade point average and the exchange of scientific information (exam questions) through social networks. There is also a link between social media use and poor academic performance, social media addiction, learning and receiving questions and course questions. However, the effect of social networks on the quantitative performance of students is moderate and its effect on other educational activities of students is low. Conclusion: Online social networks can be used as an appropriate way of interaction between students, as well as between teachers and students to convey scientific content, share questions and problem-solving skills, and help each other understand the correct path to problem solving. Although in this study, the use of virtual social networks does not have a negative effect on students' quantitative academic performance, but it should be noted that membership in these networks as a group and as a channel if it creates dependency and students spend a lot of time in their school hours. Can affect the quantitative academic performance of students. ===================================================================================== COPYRIGHTS  ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

Manipulation of photoperiod in growth factors of beluga sturgeon Huso huso

The beluga sturgeon is considered as the most important species for caviar production. This study aimed to evaluate effects of photoperiod manipulation on growth factors of beluga sturgeon. The six photoperiod regimes (light: dark cycle) including natural photoperiod (control), 24L : 0D, 16L : 8D, 12L : 12D, 8L : 16D and 0L : 24D with the three replicates. The treatment 5 (8L: 16D) gained the greatest final weight (2194.4 g) after 73 rearing days and besides, the treatments 4, 3 and 1 (12L : 12D, 16L : 8D, and Control) can be considered as the good photoperiod regimes for beluga sturgeon. The continuous light (24L : 0D) and continuous dark (0L : 24D) significantly (P < 0.05) reduced the final weight of fish to 1804.2 g and 1976.1 g, respectively. Regulated photoperiod significantly improve growth rate and food conversion ratio of beluga sturgeon

Molecular weight effects on chain pull-out fracture of reinforced polymeric interfaces

Using Brownian dynamics, we simulate the fracture of polymer interfaces reinforced by diblock connector chains. We find that for short chains the interface fracture toughness depends linearly on the degree of polymerization $N$ of the connector chains, while for longer chains the dependence becomes $N^{3/2}$. Based on the geometry of initial chain configuration, we propose a scaling argument that accounts for both short and long chain limits and crossover between them.Comment: 5 pages, 3 figure

The Goldbeter-Koshland switch in the first-order region and its response to dynamic disorder

In their classical work (Proc. Natl. Acad. Sci. USA, 1981, 78:6840-6844), Goldbeter and Koshland mathematically analyzed a reversible covalent modification system which is highly sensitive to the concentration of effectors. Its signal-response curve appears sigmoidal, constituting a biochemical switch. However, the switch behavior only emerges in the "zero-order region", i.e. when the signal molecule concentration is much lower than that of the substrate it modifies. In this work we showed that the switching behavior can also occur under comparable concentrations of signals and substrates, provided that the signal molecules catalyze the modification reaction in cooperation. We also studied the effect of dynamic disorders on the proposed biochemical switch, in which the enzymatic reaction rates, instead of constant, appear as stochastic functions of time. We showed that the system is robust to dynamic disorder at bulk concentration. But if the dynamic disorder is quasi-static, large fluctuations of the switch response behavior may be observed at low concentrations. Such fluctuation is relevant to many biological functions. It can be reduced by either increasing the conformation interconversion rate of the protein, or correlating the enzymatic reaction rates in the network.Comment: 23 pages, 4 figures, accepted by PLOS ON

A topological classification of convex bodies

The shape of homogeneous, generic, smooth convex bodies as described by the Euclidean distance with nondegenerate critical points, measured from the center of mass represents a rather restricted class M_C of Morse-Smale functions on S^2. Here we show that even M_C exhibits the complexity known for general Morse-Smale functions on S^2 by exhausting all combinatorial possibilities: every 2-colored quadrangulation of the sphere is isomorphic to a suitably represented Morse-Smale complex associated with a function in M_C (and vice versa). We prove our claim by an inductive algorithm, starting from the path graph P_2 and generating convex bodies corresponding to quadrangulations with increasing number of vertices by performing each combinatorially possible vertex splitting by a convexity-preserving local manipulation of the surface. Since convex bodies carrying Morse-Smale complexes isomorphic to P_2 exist, this algorithm not only proves our claim but also generalizes the known classification scheme in [36]. Our expansion algorithm is essentially the dual procedure to the algorithm presented by Edelsbrunner et al. in [21], producing a hierarchy of increasingly coarse Morse-Smale complexes. We point out applications to pebble shapes.Comment: 25 pages, 10 figure