Geodesic equation in kk-Minkowski spacetime

In this paper, we derive corrections to the geodesic equation due to the $k$-deformation of curved space-time, up to the first order in the deformation parameter a. This is done by generalizing the method from our previous paper [31], to include curvature effects. We show that the effect of $k$-noncommutativity can be interpreted as an extra drag that acts on the particle while moving in this $k$-deformed curved space. We have derived the Newtonian limit of the geodesic equation and using this, we discuss possible bounds on the deformation parameter. We also derive the generalized uncertainty relations valid in the non-relativistic limit of the $k$-space-time.Comment: 11 pages, references adde

Caries Incidence in Children With Regard to Their Oral Hygiene Habits and Past Caries Experience

Incidencija karijesa u djece često je u vezi s određenim životnim navikama svakoga pojedinca. Višečimbenična uzrokovanost zubnoga karijesa otežava nam djelovanje na njegove etiološke čimbenike nastanka, ali dobro poznavanje tih čimbenika može nom pomoći u prevenciji karijesa kao najhumanijem i najekonomičnijem načinu djelovanja protiv krijesa, danas još uvijek vrlo značajnog javnozdravstvenog problema. Svrha ovoga rada bila je prosuditi određene pravilnosti u incidenciji karijesa u djece u mliječnoj i trajnoj denticiji s obzirom na kliničke i nekliničke varijable koje se mogu prikupiti u svakodnevnom kliničkom radu. Istraživanje je provedeno na 301 ispitaniku, stanovnicima Petrinje i Topuskog. Dob ispitanika bila je od 3 do 6 i 11 do 14 godine. U mlađoj dobnoj skupini sudjelovalo je 74 ispitanika, a u starijoj 227. Svaki od ispitanika bio je podvrgnut istome postupku. Upitnikom se pojedinačno istražila razina i način provedbe oralne higijene, uporaba dodatnih sredstava za njezino održavanje (antimikrobna sredstva, fluoridi), prehrambene navike, sastav konzumiranih namirnica te društveno-ekonomski status. Klinički pregled napravio je iskusan ispitivač. Nalaz je obuhvaćao dentalni status, određivanje količine stimulirane sline, procjena indeksa oralne higijene (Green-Vermillion), a zabilježeno je i postojanje ortodontske anomalije. Na osnovi prikupljenih i statistički obrađenih podataka došlo se do sljedećih zaključaka: djeca ruralnog i subruralnoga dijela naše zemlje, a osobito iz ratnih područja, pokazuju vrlo visoke vrijednosti dmft/DMFT i i dmfs/DMFS indeksa. DMFT indeks iznosio je 6,67, a dmft 7,7. Dobivena vrijednost SiC indeksa iznosila je 10,89. Na temelju dobivenih rezultata možemo zaključiti da smo još veoma daleko od postavljenih ciljeva WHO i FDI za unapređenje oralnoga zdravlja .Postoji jako velik postotak ortodontskih anomalija, 68,72% u starijoj populaciji i 39,19% u mlađoj ispitnoj skupini. Istraživanjem je potvrđeno određeno pravilo distribucije karijesnih lezija prema zubu i čeljusti. Ta spoznaja, uz prikupljanje nekliničkih varijabli, može uvelike koristiti u svakodnevnoj kliničkoj praksi te omogućiti brzo i točno dijagnosticiranje. Tada se uz pravilnu preventivu i kurativnu skrb lakše može postići razina oralnoga zdravlja.Caries incidence in children is frequently connected to certain life habits of each individual. Multifactorial etiology of dental caries make it difficult to act on etiological factors, but if we get to know them better it can help us to prevent tooth decay as one of the most humane and economical ways of acting against caries, which is still an important issue of public health. The aim of this study was to establish certain regularities in caries incidence in children during primary and permanent dentition, with regard to clinical and nonclinical variables which can be gathered in everyday clinical work. The study was conducted on 301 subjects, inhabitans of Petrinja and Topusko. The subjects were age from 3-6 and 11-14 years. Seventy-four subjcts participated in the younger age group and 227 in the older. All the subjects were under the same protocol. The questionnaire examined the level of oral hygiene, use of additional supplements (antibacterial agents, fluorides), eating habits, nutrition and socio-economical status. Clinical examination was made by one experienced examiner. It consisted of a dental examination, determination of the quantity of stimulated saliva and evaluation of oral hygiene index (Green-Vermillion). Orthodontic anomaly was also noted. On the basis of the collected and statistically processed data we reached the following conclusion: children in rural an sub-rural areas of Croatia, especially in parts affected by the recent war, show very high values of dmft/DMFT. DMFT index was 6.67 and dmft 7.7. The obtained value of SiC index was 10.89. On the basis of these results we can conclude that we are still far away from the goals set by WHO and FDI to improve oral health.We also found a very high percentage of orthodontic anomalies, from 68.72% in the older group to 39.19% in the younger. The study confirmed the rule of the distribution of caries lesions towards the tooth and jaw. This knowledge, with the collecting of non-clinical variables, can be effectively used in everyday clinical practice and allows quick and accurate diagnosis with the right preventive and curative care to improve the level of oral health

Electrodynamics on κ\kappa-Minkowski space-time

In this paper, we derive Lorentz force and Maxwell's equations on kappa-Minkowski space-time up to the first order in the deformation parameter. This is done by elevating the principle of minimal coupling to non-commutative space-time. We also show the equivalence of minimal coupling prescription and Feynman's approach. It is shown that the motion in kappa space-time can be interpreted as motion in a background gravitational field, which is induced by this non-commutativity. In the static limit, the effect of kappa deformation is to scale the electric charge. We also show that the laws of electrodynamics depend on the mass of the charged particle, in kappa space-time.Comment: 16 pages,minor changes, paragraph added on page 13, two new references added, to appear in Phys.Rev.

RECONSTRUCTION OF EXISTING LIVESTOCK FEED PRODUCTION PLANTS BY ADDING A HYDRAULIC ADDER

Recipes determine the quality of livestock feed and the hydraulic adders are one of the elements determining if the given recipe will be carried out. Generally, construction of existing adders does not allow accomplishment of that aim i.e. they do not meet recipe requirements. Consequently, researches which determined deviations in ingredient adding present with existing adders and with the experimental hydraulic adder were conducted. The research was conducted for two years (2005 and 2006) in two livestock feed factories in the Republic of Croatia on samples of feed mixtures for pigs weighing up to 15 and 25 kilos. Relative error was the means for comparison of weighing deviations between the hydraulic adder and the adders powered by means of an electric motor. Research results indicate that none of the two observed livestock feed production plants in 30 repetitions for two kinds of feed mixture showed a feed mixture weighing that would correspond to the specifications in the recipe. Additionally, hydraulic adders showed a greater precision in adding fish meal, extruded soybean and soybean meal when compared with the adders powered by means of an electric motor. However, the adders powered by means of an electric motor showed greater precision in adding corn. Based on the research results it can be concluded that using hydraulic adders instead of the adders powered by means of an electric motor will result in more accuracy in dosing ingredients with fine and middle granularity, whereas this can not be applied to dosing coarse grained ingredients

Vertebral Artery Hypoplasia – Sex-Specific Frequencies in 36 Parent-Offspring Pairs

The major interest in vertebral artery (VA) hypoplasia comes from its possible connection to migraines with aura as well as from the fact that it is one of the risk factors for a stroke. Therefore, the aim of this preliminary study was to investigate the mode of inheritance of VA hypoplasia. Initially, color Doppler of VA was performed in 64 firstand second-degree relatives of 33 probands, and the presence of VA hypoplasia was confirmed according to the already established criteria. Since a higher prevalence of VA hypoplasia (15.6%) in probands’ relatives in comparison with 2.34% in the general population of Croatia was indicative of a strong familial predisposition for this condition, an analysis of family data by means of Pearson’s chi-square statistics has been performed. In this analysis, the observed sex-specific frequencies of 36 parent-offspring pairs composed only of affected parent and his/her (affected or non-affected) offspring are compared to the frequencies as expected under eight proposed models. For both – autosomal and X-linked monogenetic inheritance – four hypotheses have been chosen, assuming that the individuals having the affected allele (in combination with a healthy one) have 100%, 50%, 40% and 0% chances of developing VA hypoplasia. Out of eight tested models only two – completely dominant and completely recessive X-linked models – were rejected. But, from the six non-rejected models, goodness-of-fit statistics showed that the hypothesis of X-linked inheritance of VA hypoplasia with the »healthy« allele being stronger (60% effect on phenotype) – almost perfectly fit the data ( 2 = 2.0023; df = 7; p = 0.9597). Further research encompassing a more enlarged family sample is needed to confirm the present findings

Differential structure on kappa-Minkowski space, and kappa-Poincare algebra

We construct realizations of the generators of the $\kappa$-Minkowski space and $\kappa$-Poincar\'{e} algebra as formal power series in the $h$-adic extension of the Weyl algebra. The Hopf algebra structure of the $\kappa$-Poincar\'{e} algebra related to different realizations is given. We construct realizations of the exterior derivative and one-forms, and define a differential calculus on $\kappa$-Minkowski space which is compatible with the action of the Lorentz algebra. In contrast to the conventional bicovariant calculus, the space of one-forms has the same dimension as the $\kappa$-Minkowski space.Comment: 20 pages. Accepted for publication in International Journal of Modern Physics

SURFACE AND DEPTH WHEAT SEED DISTRIBUTION IN THE DIRECT SOWING

Tijekom istraživanja postavljen je sjetveni pokus na dva pokušališta na površinama PZ “Jankovci” u Vukovarsko-srijemskoj županiji. Istraživana je uzdužna i poprečna raspodjela sjemena te raspodjela sjemena po dubini. Analiza navedenih raspodjela obavljena je nakon nicanja usjeva, a dobiveni podaci obrañeni su i prezentirani standardnim znanstveno-statističkim metodama, uz podršku programskog paketa EXCEL 5.0. Rezultati istraživanja ukazuju na nezadovoljavajuću raspodjelu sjemena po površini (uzdužna i poprečna) i dubini, što je podudarno s dosadašnjim istraživanjima. Dakle, izravnom sjetvom pšenice štedi se energija, povećava se produktivnost rada, obavlja se sjetva u kraćem i optimalnom roku u odnosu na konvencionalnu sjetvu, ali i nadalje ostaje problem nezadovoljavajuće raspodjele sjemena.In the research the sowing experiment was established at two experimental sites belonging to “PZ Jankovci” in Vukovarsko-srijemska county. Both the lengthwise and the crosswise seed distributions were examined as well as the depth distribution. The seed germination was followed by an analysis of the above mentioned distributions and the data were processed and presented using the standard scientific and statistical methods supported by EXCEL 5.0 programme package. The results of the research show an unsatisfactory seed distribution over the surface (both lengthwise and crosswise) as well as over the depth, which is in a close relationship with the previous researches of the sowing quality when standard agrotechnics was used. Therefore, comparing the conventional sowing with the direct wheat sowing the latter saves energy, increases working efficiency, the sowing process is shorter and it is performed in an optimum period of time etc. but the problem of an unsatisfactory seed distribution still remains