International Journal of Sciences

Online ISSN: 2305-3925
This paper is proposing some physics problems from a book, De Motu Gravium Naturaliter Descendentium, written by Evangelista Torricelli, with the aim of showing how physics was taught in a university, that of Pisa, in the 17th century.
The paper shows recurrence plots obtained from time series of the level variations of four lakes in Africa (Nasser, Tana, Chad and Kainji). The data, coming from remote sensing, are provided by the United States Department of Agriculture. The recurrence plots allow a good visual comparison of the behaviours of local drainage basins.
Cameraman and the corresponding bi-level black and white image, for threshold 176. The table shows the optimized thresholds obtained using T-entropy and κ-entropy, for several values of entropic indices. Note again, that in the limit q 1  , Tsallis entropy provides Shannon result, and for κ 0  , Kaniadakis entropy becomes Shannon  
Microscopic image of cells (courtesy Kristian Peters, Wikipedia) in gray-level rendering and the corresponding bi-level image. The table is showing the optimized thresholds obtained using T-entropy and κentropy. As we did for Lena and Cameraman, the image is segmented in a bi-level black and white image according to the given threshold; the number of edge pixels between black and white regions are calculated. If we assume the "best" bi-level image being that having the largest number of edge pixels, the threshold to choose is 150 from T-and κ-entropies. Again, the best result corresponds to the Shannon limit.
The maximum entropy principle is often used for bi-level or multi-level thresholding of images. For this purpose, some methods are available based on Shannon and Tsallis entropies. In this paper, we discuss them and propose a method based on Kaniadakis entropy.
A quadrant.
-Curves of altitude (almucantar) and azimuth on the astrolabe, from the book entitled " Dell'Uso et Fabbrica dell'Astrolabio " , by Egnatio Danti, Giunti, Firenze, 1578 [25].  
-On the left, an attempt of reconstruction made by the Rear Admiral Jean Theophanidis [29] of the Antikythera mechanism and, on the right, the al-Biruni mechanism, adapted from Ref.28.  
Al-Biruni (973-1048) was one of the greatest scientists of all times. He was an astronomer, mathematician and philosopher, and studied physics and natural sciences. In this paper, we will discuss some of his experimental methods and some instruments he used.
- Time series of Harry’s friends Ron Weasley, Hermione Granger, Hagrid the gamekeeper and Professor Dumbledore, and also of his “enemies” Dudley Dursley and Draco Malfoy. We are supposing a hypothetic text containing the novel in 200 pages. The functions represent the occurrence in a page of the characters in a barcode-like image. If the name of the characters appears in the page once or more times, the function has a value equal to one, otherwise, the value of the function is zero. Given a page, if the function is zero we have a white bar, if the value is one we have a black bar. 
- Recurrence plots are useful to reveal complex spatial and temporal details of the time series. Having these plots as models, we can create some occurrence matrices for time series shown in the Figure 1. Here we see square plots, where both axes are time axes; the number of the page represents time. The black dots represent the occurrence of the character in the page of the novel. Of course, these matrices provide the same information of the barcodes. 
- Using different colours, we can represent on the same plot the co-occurrence of several characters. Here we have the co-occurrence plots over time of Hagrid with Dumbledore, Dudley, Ron, Hermione and Draco. The pink colour represents Hagrid’s occurrences, whereas the light blue that of the other character. The black dots represent the co-occurrence of both characters in the same page. We can see also the co-occurrence matrices of Ron with Dumbledore, Dudley, Hagrid, Hermione and Draco: in this case, the pink colour represents the occurrence of Ron and the light blue that of the other character. 
– Co-occurrence plot for three characters: Hagrid, Ron and Hermione. The black dots represent the presence of them in the same page. 
Recently, it has been proposed to analyse the literary works, plays or novels, using graphs to display the social network of their interacting characters. In this approach, the timeline of the literary work is lost, because the storyline is projected on a planar graph. However, timelines can be used to build some time series and analyse the work by means of vectors and matrices. These series can be used to describe the presence and relevance, not only of words in the text, but also of persons and places portrayed in the drama or novel. In this framework, we discuss here an approach with co-occurrence matrices plotted over time, concerning the presence of characters in the pages of a novel. These matrices are similar to those appearing in recurrence plots.
The colours can be created by white, which is brightness, intensity and purity. We can relax one, two or all these three features to obtain seven colours, as in the calculus of combinations. The relaxation of one of the white features is rendered by a grey circles. The same we can do from the black. 
The seven colours from white and the seven colours from black are merging in “average” colours, which gives a circle of seven colours [15]. White, black and these seven colours provide nine colours. 
An example from the palette of Paint software. We see a light green and a dark green. In any case, it is green.
Here I am proposing a translation and discussion of the De Colore, one of the short scientific treatises written by Robert Grosseteste. In this very short treatise of the mid-1220s, Grosseteste continued the discussion on light and colours he started in the De Iride. He describes two manners of counting colours: one gives an infinity of tones, the other counts seven colours. In both cases, colours are created by the purity or impurity of the transparent medium when light is passing through it. This medieval framework survived until Newton's experiments with prisms.
- Daily exchange rate Euro - US Dollar and Euro - GB Pound from July 1, 2010 to July 1, 2014. We can see several periods of oscillation, represented by checkerboard textures, and periods of random walks with a texture having typical circles. 
- Here the two recurrence plots of Figure 1 are shown together. In blue we see the exchange rate Euro - US Dollar and in red the exchange rate Euro - GB Pound. We can see the periods of time when the two rates oscillate or are on random walk as often coincident. 
- Daily exchange rate Euro - US Dollar and Euro - GB Pound in the recurrence plots created using VRA with Euclidean distances. 
- Recurrence plots of exchange rates between Euro and Japanese Yen: in the upper image, plotted according to Eqs.3 and 4, in the lower image plotted with VRA. The VRA image shows a texture transition, that is a visual discontinuity, on April 4, 2013. On that day, markets boosted by announcements of the Bank of Japan. As reported in [25], “yen fell more than 3 percent against the dollar and 4 percent against the euro”. 
Used to investigate the presence of distinctive recurrent behaviours in natural processes, the recurrence plots can be applied to the analysis of economic data, and, in particular, to the characterization of exchange rates of currencies too. In this paper, we will show that these plots are able to characterize the periods of oscillation and random walk of currencies and enhance their reply to news and events, by means of texture transitions. The examples of recurrence plots given here are obtained from time series of exchange rates of Euro.
The frequency of the emitted light depends on the band-gap energy of p-n junction. This gap exists between the bottom of the conduction band and the top of the valence band. In semiconductors, we can have direct or indirect band gaps. A certain crystal momentum, and its corresponding k-vector in the Brillouin Zone, characterizes the minimum energy state of the conduction band; another k-vector gives the maximum energy state of the valence band. If these two k-vectors are the same, we have a direct gap: if different, there is an indirect gap. Therefore, the bandgap is direct if an electron can recombine with a hole of the same momentum, emitting a photon. This photon has a relatively large wavelength, and therefore a negligible wavenumber, when compared to the k-vectors of electrons. Therefore, the conservation of total crystal momentum is easily fulfilled. When the gap is indirect, the probability of a photon emission is very low and electron must transfer momentum to the phonons of the crystal lattice [20]. 
The fabricated LED chips are mounted in a package that consists of two electrical leads, a transparent optical window for the escape of light and thermal paths for heat dissipation. Typical package for low-power device is given in the figure on the left. In the upper part we see an image of a LED and in the lower part a schematic representation of the diode, in the case of a GaN device. The active device is bonded or soldered to the bottom of a cup-like depression, the reflector cup, with one of the lead wires, usually the cathode lead. A bond wire connects the LED top contact to the other lead wire, usually the anode lead. This package is frequently referred to as the 5mm or T1-3/4 package [26]: it is encapsulated in a transparent material having a hemispherical shape to have a normal angle of incidence of the rays of light to the encapsulate-air interface. The standard 5mm LED package is not suited to have a sufficient heat transfer to maintain the LED cool during operation. Therefore, a new package for high-power LED had been developed: it is the flip-chip package that we can see in the image on the right, with its schematic view [26,27]. Let us note that the active region is often made by multi quantum wells (the 3D model is a Wikipedia/Tosaka|Tosa courtesy). 
Red and green light-emitting diodes (LEDs) had been produced for several decades before blue emitting diodes, suitable for lighting applications, were widely available. Today, we have the possibility of combining the three fundamental colours to have a bright white light. And therefore, a new form of lighting, the solid-state lighting, has now become a reality. Here we discuss LEDs and some of their applications in displays and lamps.
The maximum entropy principle is largely used in thresholding and segmentation of images. Among the several formulations of this principle, the most effectively applied is that based on Tsallis non-extensive entropy. Here, we discuss the role of its entropic index in determining the thresholds. When this index is spanning the interval (0,1), for some images, the values of thresholds can have large leaps. In this manner, we observe abrupt transitions in the appearance of corresponding bi-level or multi-level images. These gray-level image transitions are analogous to order or texture transitions observed in physical systems, transitions which are driven by the temperature or by other physical quantities.
Cartesian inertial frame and rotating frame, having the same origin at rest. 
Jerk is the derivative of acceleration with respect to time and then it is the third order derivative of the position vector. Hyperjerks are the n-th order derivatives with n>3. This paper describes the relations, for jerks and hyperjerks, between the quantities measured in an inertial frame of reference and those observed in a rotating frame. These relations can be interesting for teaching purposes.
A geocentric world view, like in the Grosseteste's cosmology. Note the firmament above the sphere of the Zodiac. This image is adapted from an Icelandic manuscript, now in the care of the Magnusson Institute in Iceland. Courtesy: Wikipedia. 
Robert Grosseteste was one of the most prominent thinkers of the Thirteenth Century. Philosopher and scientist, he proposed a metaphysics based on the propagation of light. In this framework, he gave a cosmology too. Here we will discuss the treatise where Grosseteste proposed it, that entitled 'De luce, seu de incohatione formarum', 'On Light and the Beginning of Forms'.
Here two geoglyphs in the Nazca Desert, Peru (coordinates: 14.9997S, 75.0125W). The Nazca geoglyphs, known as the Nazca Lines, are the most famous negative geoglyphs of Peru. Included among the UNESCO World Heritage Sites in 1994, the Lines are located in the Nazca Desert, a large region between the towns of Nazca and Palpa. On the Nazca plane, the geoglyphs had been made by removing the uppermost surface, exposing the underlying ground, which has a different colour. This technique produces a “negative” geoglyph. The images on the left are as we can see in the Google Maps. On the right, the images after using the GIMP tool to change the local contrast. These images show an interesting application of this tool in archaeological investigations. 
The calculus of variations applied to the image processing requires some numerical models able to perform the variations of images and the extremization of appropriate actions. To produce the variations of images, there are several possibilities based on the brightness maps. Before a numerical model, I propose an experimental approach, based on a tool of Gimp, GNU Image Manipulation Program, in order to visualize how the image variations can be. After the discussion of this tool, which is able to strongly increase the visibility of images, the variations and a possible functional for the visibility are proposed in the framework of a numerical model. The visibility functional is analogous to the fringe visibility of the optical interference.
The angles of the Gothic cathedrals in France on a polar diagram. The red lines correspond to the largest sunrise amplitude for the North and South of France. We see that only three building are exceeding an orientation with the sunrise. They are at Metz, Chartres, and Le Mans.  
Here the orientation of the Gothic cathedrals in France is discussed and investigated using the satellite maps. Except a few of them, these buildings have the apse facing the rising sun, according to a practice adopted during the middle age.
The objective of this study is to explore the effects of amygdala kindling on estrus cycle and ovarian morphology. Thirty-five female rats at the age of 8 weeks were randomly designated to electrode kindled, sham-kindled, and normal controls. Kindled rats were implanted with kindling electrodes in the left basolateral amygdala and kindled by brief suprathreshold stimulations with a bipolar electrode. Estrous cycles were daily monitored through vaginal smears. Electrographic and behavioral seizures were recorded and ovarian morphology was evaluated by light and electron microscopies. Our results showed that the kindled rats lost their ovarian periodicity displayed significant ovarian enlargement. H&E staining revealed increased number of growing follicles and total follicles, as well as polycysts in the ovaries of the kindled animals compared to sham and control animals. Ultrastructural study detected numerous apoptotic granulosa cells in growing follicles and thecal cell hyperplasia with secretary granules in the thecal cells in the kindled rats. The results suggest that amygdala kindling is a risk factor for the development of polycystic ovary syndrome.
Star forts were the fortifications composed of many triangular bastions, created from 1520s,to replace those of the medieval age, and able of resisting the gunpowder weapons. These fortifications were also defined as“trace italienne”, because they were first planned and built in Italy. Some of these forts are still existing today, many had been destroyed or dismantled in the past. Here we will discuss the case of one of them, cancelled by an urban planning for expanding the town. It is the Citadel of Turin, of which only the Mastio survived.
The effect of geographical origin on the zootechnical parameters of tilapias is very poorly documented, unlike production systems and farming methods. In this study, the growth and survival characteristics of Oreochromis niloticus individuals were analyzed in relation with their waterway of origin, sex and age at experimental fishing. Durung the rearing, the duplicate groups were constituted keeping the 2 sexes (male vs female) separately. Fingerlings were fed using a granulated commercial fish feed (35% of proteins; 3 mm in diameter). Apart from chlorophyll «a», 3 phytoplankton and 5 zooplankton species were also available in the rearing tank. The body weight, total length, standard length, average weight gain, nutritive quotient and survival rate were similar (p>0.05) between lake Toho and Couffo river but weaker at these two waterways than Ouémé river (p<0.05). The ponderal and linear specific growth rates were significantly identical between lake Toho and Couffo river but more important (p<0.001) in these two waterways than Ouémé river. The majority of the individuals indicated an allometric growth (b<3), which is less desirable in fish farming. In short, 2 populations were identified: the group constituted by Ouémé river and the one including lake Toho and Couffo river. It appears important to lead actions (selective breeding, crossbreeding) to improve the zootechnical performances of these local populations in order to promote their aquaculture.
When asked to define the electric light, we immediately think of the artificial lighting produced by incandescent and gas-discharge lamps. But in the past, the electric lamps had a rather different form. About 1870, electric lighting was based on carbon-arc devices powered by magneto-electric generators. We find an interesting and detailed description of this technology in an essay written by Jacob Abbott, an American writer of children's books, and published by Harper's Magazine in the August Issue of that year. From this Abbott's essay, we start our discuss of the electric lighting system of the 19th century.
Top-cited authors
Amelia Carolina Sparavigna
  • Politecnico di Torino
Fouad Mesquine
  • Cadi Ayyad University
Ebenezer Owusu-Sekyere
  • University for Development Studies
Bhoj Raj Pathak
  • Department of Forest, Nepal
Yi Xie
  • Beijing Forestry University