Steganographic method based on hidden messages embedding into Bezier curves of SVG images

The description of the steganographic method for embedding the digital watermark into image vector files of the SVG format is given. Vector images in SVG format can include elements based on Bezier curves. The proposed steganographic method is based on the splitting of cubic Bezier curves. Embedding hidden information involves splitting cubic Bezier curves according to the digital watermark given as numerical sequence. Algorithms of direct and reverse steganographic transformation are considered for proving the authenticity and integrity of a digital vector image. The StegoSVG library has been developed to implement forward and reverse steganographic transformations. The developed desktop application that implements the method is briefly described.

Topological Essence of the Concept “Limit of a Numerical Sequence” in the General Mathematics

High school mathematics includes a number of extremely important concepts, including the concept of the limit of the number sequence. However, most students when learning it do not understand it with certainty, but only accept it to apply it to solve exercises. This paper aims to give a topological essence of the concept of limit of a sequence and present some methods for teaching this concept in general school in Viet Nam. The Paper consists of four parts. Part 1 presents an introduction to the definition of “Limit of a sequence”, part 2 deals with Some properties derived from definitions and notes in teaching, part 3 covers the Mathematical essence of the concept limit of a number sequence and part 4 talks about Defining topology on the set of real numbers. In each section, we include comments to help teach these notions and concepts. In each section, we make comments and observations to teach these concepts better.

A simplified procedure to improve the usability of hydrodynamic modelling software in regenerative urban design

Densely urbanized areas are greatly exposed to the risks from climate change as reported by IPCC in 2018. In particular, compact urban settings afflicted by heavy storms and droughts, coupled with the intensification of the Urban Heat Island (UHI) effect and incremental heat waves require a requalification of the outdoor environment that accommodates for both strategic water management and enhanced microclimatic conditions. The present study proposes simplified procedures to enable the application of complex hydrodynamic modelling software (SWMM), by non-expert users (such as planners and designers), in the preliminary phases of an urban space project according to a water-sensitive urban design approach. In the paper, Italian multi-level regulations aimed at controlling the impacts of excessive rainfall in urban areas are taken into account as well as the integration of circular water management systems with evaporative cooling strategies. The proposed procedure is focused on two aspects: 1- to simplify the steps needed to convert the existing climatic data to provide a numerical sequence, to insert into the software; 2- to define a set of pre-compiled and multi-purposed solutions toolkits for the design of urban spaces that can be imported into the software through an external database.

GENERALIZED CHARACTERISTICS TYPES OF EXCHANGE TRADING STRATEGIES

It has been determined that online trading is associated with a significant degree of risk, which can be reduced through a thorough and systematic approach to the choice of exchange trading strategies. The strategy (system) of exchange trading is a personal trading rules that take into account the market situation, knowledge and understanding of the trader of this situation, as well as the trader’s wishes regarding the profitability of trading, taking into account the risks. Trading systems based on technical analysis of stock charts are considered: trend (based on the assumption that the price will rise or fall according to market trends), flat (assumes that prices change within a corridor that has clearly defined borders, supported by levels of resistance or support), counter-trend (involves determining the turning point of the price movement), trading on forex patterns (involves determining the figures of graphical analysis of stock charts, resulting in, according to statistics, there is a high probability predict price movements), wave analysis (assumes that market behavior depends on the psychology of participants, which is expressed in the impulsiveness of behavior), breakthrough volatility (assumes that a significant event is the actual exit of the price from the established channel, creating opportunities for trends), session trade (involves work in the market within a specific trade session), trading at Fibonacci levels (assumes that the price should create adjustments to the trend, reflecting the special levels, which are based on the numerical sequence of Fibonacci), scalping (provides trading within the trading day and is characterized by small levels of take profits and relatively large levels of stop-losses) and universal (provide a different combination of the above systems depending on the preferences and experience of the trader). It is concluded that all types of trading systems can be profitable, but first of all it all depends on the knowledge and skills of the person who carries out trading operations.

Cyber-attack detection via non-linear prediction of IP addresses: an innovative big data analytics approach

Computer network systems are often subject to several types of attacks. For example, an excessive traffic load sent to a web server for making it unusable is the main technique introduced by the Distributed Denial of Service (DDoS) attack. A well-known method for detecting attacks consists in analyzing the sequence of source IP addresses for detecting possible anomalies. With the aim of predicting the next IP address, the Probability Density Function of the IP address sequence is estimated. Anomalous requests are detected via predicting source’s IP addresses in future accesses to the server. Thus, when an access to the server occurs, the server accepts only the requests from the predicted IP addresses and it blocks all the others. The approaches used to estimate the Probability Density Function of IP addresses range from the sequence of IP addresses seen previously and stored in a database to address clustering, for instance via the K-Means algorithm. Instead, the sequence of IP addresses is considered as a numerical sequence in this paper, and non-linear analysis of this numerical sequence is applied. In particular, we exploited non-linear analysis based on Volterra Kernels and Hammerstein models. The experiments carried out with datasets of source IP address sequences show that the prediction errors obtained with Hammerstein models are smaller than those obtained both with the Volterra Kernels and with the sequence clustering based on the K-Means algorithm.

Organização do Ensino do Conceito de Número no Primeiro Ano de EscolarizaçãoOrganization of Teaching the Concept of Number in the First Year of Schooling

ResumoEste artigo tem como objetivo investigar o processo de apropriação do conceito de número pelos escolares que frequentam o primeiro ano do ensino fundamental. Para isso, desenvolvemos um experimento formativo, uma metodologia de caráter científico que permite investigar o processo de desenvolvimento dos sujeitos e as formas de organizar o ensino. Neste experimento, elaboramos uma unidade didática sobre o conceito de número. No processo de elaboração e desenvolvimento do experimento formativo foi possível investigarmos a interrelação entre a atividade de estudo e as demais atividades humanas, em especial, o jogo de papéis. Em síntese, ao desenvolver essa investigação, avaliamos que na aprendizagem do conceito de número os escolares realizaram, a princípio, ações pautadas na percepção sensorial da realidade, o que significa que as abstrações e generalizações elaboradas pelas crianças tinham como base a lógica do pensamento empírico. Contudo, com a intervenção orientada pela pesquisadora, verificamos que as crianças começaram a compreender que a essência do conceito de número não existe sem as relações entre as grandezas, sejam elas discretas ou contínuas, revelando assim o processo de formação do pensamento teórico. A partir dos dados analisados nessa pesquisa, concluímos que é possível superar práticas pedagógicas tradicionais que reduzem o conceito de número a memorização, cópia e recitação da sequência numérica, a partir da sistematização de ações de ensino que priorizam a aprendizagem desse conceito a partir das relações entre as grandezas.Palavras-chave: Ensino de Matemática, Atividade de estudo, Tarefa de estudo, Jogo de papéis, Número.AbstractThis article aims to investigate the process of appropriation of the concept of number by students of the first year of elementary school. For this, we developed a formative experiment, a scientific methodology that allows investigating the process of development of the subjects and the ways of organising teaching. In this experiment, we developed a didactic unit on the concept of number. In the process of elaborating and developing the formative experiment, it was possible to investigate the interrelationship between the study activity and other human activities, in particular, the role play. In summary, when developing this investigation, we evaluated that in learning the concept of number, students performed, at first, actions based on the sensory perception of reality, which means that the abstractions and generalisations the children elaborated were based on the logic of empirical thinking. However, with the intervention guided by the researcher, we found that the children began to understand that the essence of the concept of number does not exist without the relationships between the quantities, whether they are discrete or continuous, thus revealing the process of forming theoretical thinking. From the data analysed in this research, we conclude that it is possible to overcome traditional pedagogical practices that reduce the concept of number to memorisation, copying, and recitation of the numerical sequence, based on the systematisation of teaching actions that give priority to the learning of this concept based on relationships between the quantities.Keywords: Mathematics teaching, Study activity, Study task, Role play, Number.ResumenEste artículo tiene como objetivo investigar el proceso de apropiación del concepto de número por parte de los estudiantes del primer año de primaria. Para ello, desarrollamos un experimento formativo, que constituye una metodología científica que permite investigar el proceso de desarrollo de las asignaturas y las formas de organizar la enseñanza. En este experimento, se elaboró una unidad didáctica sobre el concepto de número. En el proceso de elaboración y desarrollo del experimento formativo, fue posible investigar la interrelación entre la actividad de estudio y otras actividades humanas, especialmente el juego de roles. En resumen, al desarrollar esta investigación, evaluamos que, al aprender el concepto de número, los estudiantes realizaron, al principio, acciones basadas en la percepción sensorial de la realidad. Esto significa que la abstracción y generalización elaborada por los niños se basaron en la lógica del pensamiento empírico. Sin embargo, con la intervención guiada por el investigador, quedó en evidencia que los niños empezaron a comprender que la esencia del concepto de número no existe sin las relaciones entre las cantidades, ya sean discretas o continuas, lo que revela el proceso de formación del pensamiento teórico. A partir de los datos materializados, la investigación concluyó que es posible superar las prácticas pedagógicas básicas que originan el concepto de número, memorización, copia y recitación de la secuencia numérica, a partir de la sistematización de acciones docentes que priorizan el aprendizaje de este concepto desde las relaciones entre cantidades.Palabras-clave: Enseñanza de las matemáticas, Actividad de estudio, Tarea de estudio, Juego de papeles, Número.

Ants Can Anticipate the Following Quantity in an Arithmetic Sequence

Workers of the ant Myrmica sabuleti have been previously shown to be able to add and subtract numbers of elements and to expect the time and location of the next food delivery. We wanted to know if they could anticipate the following quantity of elements present near their food when the number of these elements increases or decreases over time according to an arithmetic sequence. Two experiments were therefore carried out, one with an increasing sequence, the other with a decreasing sequence. Each experiment consisted of two steps, one for the ants to learn the numbers of elements successively present near their food, the other to test their choice when they were simultaneously in the presence of the numbers from a previously learned sequence and the following quantity. The ants anticipated the following quantity in each presented numerical sequence. This forethinking of the next quantity applies to numerosity, thus, to concrete items. This anticipatory behavior may be explained by associative learning and by the ants’ ability to memorize events and to estimate the elapsing time.

Smoothness and approximative properties of solutions of the singular nonlinear Sturm-Liouville equation

It is known that the eigenvalues λn(n = 1, 2, ...) numbered in decreasing order and taking the multiplicity of the self-adjoint Sturm-Liouville operator with a completely continuous inverse operator L^{−1} have the following property (*) λn → 0, when n → ∞, moreover, than the faster convergence to zero so the operator L^{−1} is best approximated by finite rank operators. The following question: - Is it possible for a given nonlinear operator to indicate a decreasing numerical sequence characterized by the property (*)? naturally arises for nonlinear operators. In this paper, we study the above question for the nonlinear Sturm-Liouville operator. To solve the above problem the theorem on the maximum regularity of the solutions of the nonlinear Sturm-Liouville equation with greatly growing and rapidly oscillating potential in the space L2(R) (R = (−∞, ∞)) is proved. Twosided estimates of the Kolmogorov widths of the sets associated with solutions of the nonlinear SturmLiouville equation are also obtained. As is known, the obtained estimates of Kolmogorov widths give the opportunity to choose approximation apparatus that guarantees the minimum possible error.

Estimation of morphological characteristics of Seedlings of Genipa americana L. (Rubiaceae)

Genipa americana L. is a tree species with socioeconomic and environmental potential. Popularly known as jenipapeiro, it is used in the production of wood and its fruits are considered one of the main recipes of small farmers, being also used in the recovery of degraded areas. The work aimed to evaluate and compare the traditional method (Pachymeter) and digital image obtained through a photographic camera to determine the height of the plant, height of insertion of the first leaf and diameter of the neck of American genipa. The study was carried out in the Flora-action-Seedlings nursery and in the Didactics II laboratory. In the nursery, 30 seedlings were analyzed randomly. In the same numerical sequence were the seedlings on the phenotyping platform where the images were captured, with a Sony Gps Hd Avchd progressive digital camera, attached at a height of 50 cm. The diameter of the stem (CD), the total height of the plant and the height of insertion of the last leaf were measured using the free ImageJ software, using images from digital cameras. Statistical analyzes were performed with the aid of the Sigmaplot program and analyzed using descriptive statistics to estimate measures of central tendency (mean) and dispersion (standard deviation and coefficient of variation). Through the results, it is possible to observe the high proportion of the two methodologies, being validated both for the traditional methods (caliper) and for the innovative method (digital image). Where the coefficients were high, showing the accuracy of the methods. Thus, it indicates that the digital camera can be very useful to measure the total height of a plant and can also be indicated for trees, shrubs and others. According to the data obtained, it can be said that there is precision between the methodologies used with manual measurement and digital images, using the ImageJ software, and its use is recommended for the analysis of the morphological characteristics of the species Genipa americana L.

534. Halting a SARS-COV2 Outbreak in a Veterans Affairs Nursing Home

Background Health care systems have been significantly overwhelmed during the SARS-CoV-2 (SC2) pandemic. Cases in the USA have exceeded 1.9 million with over 40% of deaths occurring in nursing homes and assisting living facilities. We describe our experience in controlling an outbreak in our community living centers (CLC) Methods We retrospectively reviewed the charts of Veterans with positive nasopharyngeal (NP) RT-PCR for SC2 from March 24 to April 18, 2020 in 2 neighboring CLC units (80 bed capacity), at Northport Affairs Medical Center. Results Twenty five Veterans (24 men) tested positive for SC2. Of these, 5 remained asymptomatic, 9 got hospitalized, 6 died. No coinfection with influenza or other respiratory viruses identified. 11 health care workers (HCW) tested positive. Figure 1 shows test results by date. Table 1 summarizes the demographic characteristics, medical history, and laboratory findings. The median age was 74 years, with no difference in age between recovered and deceased, 73 vs. 77, P:0.105. Simplified acute physiology score (SAPS) II score was higher in the deceased group (P=0.001) and so were D-dimer (admission and peak levels), CRP, LDH, and peak ferritin/procalcitonin levels. There was no ICU admission. Figure 2 illustrates the CLC 1 and 2 outline of beds depicting positive cases in sequence of detection. Initial spread of the virus was fast, affecting residents and HCW. CLC visits were prohibited, floating of staff minimized, internal group activities halted, infection control measures and education on proper use of personal protective equipment provided. A SC2 (or “COVID”) unit was created in CLC1 and all patients and staff got tested. Withdrawal of isolation precautions required resolution of symptoms, and two sequential negative NP PCR tests which were obtained after 14 days from diagnosis. If the PCR was positive, a repeat test was obtained in 72 hours. 13 patients had persistent positive PCR for average 32 days (19 to 52) since diagnosis. 7/13 got tested and all were positive for SC2 IgG antibody. SARS-CoV -2 Outbreak in VA Nursing Home, Dates of Tests Bed Outline of CLCs Depicting the Location And Numerical Sequence of Positive Tests Comparison Between Recovered vs Deceased Nursing Home Veterans with COVID-19 Conclusion Controlling SARS-CoV-2 outbreaks in nursing homes is a unique challenge as the virus can spread quickly among residents and staff. Mortality rate in our cohort was 24%. Prompt, effective isolation and broad testing was instrumental in halting the SC2 (COVID-19) outbreak. Disclosures All Authors: No reported disclosures