STABILITIY OF THE SYNTAGMATIC PROBABILITY DISTRIBUTIONS

The aim of the present study is to establish criteria for the optimal sizeof a corpus that can provide stable conditional probabilities of morphologicaland/or syntagmatic types. The optimality of corpus size is defined in terms ofthe smallest sample that generates probability distribution equal to distributionderived from the large sample that generates stable probabilities. The latterdistribution we refer to as “target distribution”. In order to establish theabove criteria we varied the sample size, the word sequence size (bigrams andtrigrams), sampling procedure (randomly chosen words and continuous text)and position of the target word in a sequence. The obtained distributions ofconditional probabilities derived from smaller samples have been correlatedwith target distributions. Sample size at which probability distribution reachesmaximal correlation (r=1) with the target distribution was taken as beingoptimal. The research was done on Corpus of Serbian language. In case ofbigrams the optimal sample size for random word selection is 65.000 words,and 281.000 words for trigrams. In contrast, continuous text sampling requiresmuch larger samples to reach stability: 810.000 words for bigrams and 868.000words for trigrams. The factors that caused these differences remain unclear andneed additional empirical investigation

Having Fun in Learning Formal Specifications

There are many benefits in providing formal specifications for our software. However, teaching students to do this is not always easy as courses on formal methods are often experienced as dry by students. This paper presents a game called FormalZ that teachers can use to introduce some variation in their class. Students can have some fun in playing the game and, while doing so, also learn the basics of writing formal specifications in the form of pre- and post-conditions. Unlike existing software engineering themed education games such as Pex and Code Defenders, FormalZ takes the deep gamification approach where playing gets a more central role in order to generate more engagement. This short paper presents our work in progress: the first implementation of FormalZ along with the result of a preliminary users' evaluation. This implementation is functionally complete and tested, but the polishing of its user interface is still future work

Effects of Metallicity on the Instability Mass Ratio of Low Mass Contact Binary Systems

The orbital stability of contact binary systems has been receiving considerable attention recently. Theoretical studies indicate that merger is likely to occur at very low mass ratios, but the actual mass ratio at which merger may take place is likely to be variable and dependent on the mass of the primary. We consider the effects of metal content on the orbital stability of contact binary systems by modelling the gyration radius of a rotating and tidally distorted primary component at various values of metallicity in the range -1.25 to +0.5. We determine the instability mass ratio range for contact binary systems with a low mass primary in the range 0.6M(sun) to 1.4M(sun) at various metallicity levels and show that systems with low metallicity have an instability mass ratio lower than those with higher metal content and therefore are likely to be more stable. We illustrate the effect through light curve analysis of two otherwise very similar contact binary systems, except for different metallicity. While both would be considered unstable if metallicity was not taken into consideration, only one remains in that category after appropriate adjustments based on metallicity have been made.Comment: 9 pages, 7 Figures and 5 Tables Accepted Monthly Notices of Royal Astronomical Society (MNRAS

Structure and properties of tempo-oxidized cotton fibers

In this paper, the influence of the catalytic oxidation using water soluble and stable nitroxyl radical 2,2´,6,6´-tetramethylpiperidine-1-oxyl (TEMPO) on structure and properties of cotton fibers was studied. In particular, the selective TEMPO-mediated oxidation has become very interesting way for introduction of functional groups into cellulose fibers with the aim to obtain oxycellulose fibers with specific properties. Unmodified and modified fibers were characterized in terms of weight loss values, introduced functional groups and crystallinity index. Also, oxidized fibers were characterized in terms of the sorption, morphological, and physico-mechanical properties. The TEMPO-oxidized cotton fibers show a minimum increase of fineness (from 1.32 to 1.28 dtex) and increase of crystallinity index (up to 91.9%), while the tensile strength of fibers decreases (up to 10.82 cN/tex). By the TEMPO-mediated oxidation of cotton fibers significant amount of carboxyl groups (up to 0.795 mmol/g cell) can be introduced into cellulose fibers. Introduced hydrophilic carboxyl groups increases the sorption properties of oxidized fibers, that can be used directly or for further chemical modification

Suzbijanje kukuruzove zlatice Diabrotica virgifera virgifera

Western corn rootworm (WCR) was registered for the first time in Europe near the Surčin international airport in Serbia in 1992. The spread of WCR on the territory of Serbia and its population density increased fast. The Serbian territory was entirely populated in the following few years, while major damages occurred on corn grown for two or more years in the same field. Data on damages caused to over 140,000 ha under corn until 1999 were collected by organized monitoring. After 2000 and 2003, population abundance of D.v. virgifera, as well as the number of damaged corn fields, significantly decreased due to drought and application of crop rotation. Corn rootworm has one generation per year. It overwinters in the egg stage. Under the climatic conditions of Serbia larvae hatching starts around May 15th. The highest number of larvae on root is observed around June 20th when feeding is most intensive and plants become lodged as they lose roots. First adults emerge by the end of June. Their abundance increases during July and reaches maximum by the end of the month. From the second decade of August the abundance decreases. Adults are present in the field until the first frosts. Larvae are much more harmful and significant than adults. Larvae feed on roots or into roots by boring. Roots can be entirely destroyed under heavy attack and the host plants lodged already at the end of June. Under our climatic and agrotechnical conditions, adults are sporadic pests. Adults are a threat only when sowing is done after the optimal sowing date or in case of stubble corn sowing. Crop rotation is an efficient and most widespread means of WCR control. No damage on corn grown in crop rotation has been registered in Serbia for now. In the first year of production corn does not require protection from Diabrotica virgifera virgifera LeConte larvae. Several insecticides have performed high efficacy by application at sowing and have been registered for commercial use. On the other hand, soil insecticides have never been applied on a significant area in Serbia.Kukuruzova zlatica je prvi put registrovana 1992. godine pored međunarodnog aerodroma Surčin. Širenje zlatice po teritoriji Srbije i porast gustine njene populacije je bilo brzo. Celokupna teritorija Srbije je naseljena u narednih nekoliko godina, pri čemu su se značajne štete javile na kukuruzu u ponovljenoj setvi. Sakupljeni su podaci o štetama na preko 140.000 ha kukuruza u periodu do 1999. godine. Posle 2000. i 2003. godine brojnost popualcije D.v. virgifera kao i broj oštećenih kukuruzovih polja je značajno smanjen zbog suše i masovne primene plodoreda. Kukuruzova zlatica ima jednu generaciju godišnje. Prezimljava u stadijumu jajeta. U klimatskim uslovima Srbije piljenje larvi počinje oko 15. maja. Najveći broj larvi se nalazi na korenu kukuruza oko 20. juna kada je ishrana larvi najintenzivnija. Zbog gubitka korena dolazi do poleganja biljaka. Odrasli insekti se javljaju krajem juna. Njihova brojnost raste tokom jula i dostiže maksimum krajem tog meseca. Od druge dekade avgusta brojnost imaga opada. Odrasli insekti se mogu naći u polju sve do prvih mrazeva. Larve se hrane na korenu ili se ubušuju u njega. U slučaju velikog napada koren može biti potpuno uništen i takve biljke već krajem juna poležu. U našim klimatskim i agrotehničkim uslovima odrasli insekti su sporadične štetočine. Oni mogu biti štetni u slučajevima kasnije setve ili postrne setve. Plodored je efikasan i najrasprostranjeniji način suzbijanja kukuruzove zlatice. Do sada se u Srbiji nisu javile štete na kukuruzu u plodoredu. Stoga se u kukuruzu u plodoredu ne primenjuju zaštitne mere. Više insekticida pokazuje dobre rezultate u suzbijanju kukuruzove zlatice kada se primenjuju sa setvom i imaju dozvolu za primenu u Srbiji. Međutim, zemljišni insekticidi nisu nikada do sada primenjeni na većim površinama za suzbijanje kukuruzove zlatice

Achieving a Superhydrophobic, Moisture, Oil and Gas Barrier Film Using a Regenerated Cellulose–Calcium Carbonate Composite Derived from Paper Components or Waste

It has been a persistent challenge to develop eco-friendly packaging cellulose film providing the required multiple barrier properties whilst simultaneously contributing to a circular economy. Typically, a cellulosic film made from nanocellulose materials presents severe limitations, such as poor water/moisture resistance and lacking water vapour barrier properties, related primarily to the hydrophilic and hygroscopic nature of cellulose. In this work, alkyl ketene dimer (AKD) and starch, both eco-friendly, non-toxic, cost-effective materials, were used to achieve barrier properties of novel cellulose–calcium carbonate composite films regenerated from paper components, including paper waste, using ionic liquid as solvent. AKD and starch were applied first into the ionic cellulose solution dope mix, and secondly, AKD alone was coated from hot aqueous suspension onto the film surface using a substrate surface precooling technique. The interactions between the AKD and cellulose film were characterised by Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) showing the formation of a ketone ester structure between AKD and the hydroxyl groups of cellulose. The presence of calcium carbonate particles in the composite was seen to enhance the cellulose crystallinity. The initial high-water vapour and oxygen transmission rates of the untreated base films could be decreased significantly from 2.00 to 0.14 g m−2 d−1, and 3.85 × 102 to 0.45 × 102 cm3 m−2 d−1, respectively. In addition, by applying subsequent heat treatment to the AKD coating, the water contact angle was markedly increased to reach levels of superhydrophobicity (>150°, and roll-off angle < 5°). The resistance to water absorption, grease-permeation, and tensile strength properties were ultimately improved by 41.52%, 95.33%, and 127.33%, respectively, compared with those of an untreated pure cellulose film. The resulting regenerated cellulose–calcium carbonate composite-based film and coating formulation can be considered to provide a future bio-based circular economy barrier film, for example, for the packaging, construction and agriculture industries, to complement or replace oil-based plastics.Peer reviewe