1,675 research outputs found

    EpidemioloÅ”ki značaj određivanja olova, kadmija, bakra i cinka u kosi i trajnim zubima osoba koje žive u blizini topionice olova

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    In this paper the content of lead, cadmium, copper and zinc was analysed by atomic absorption spectrophotometry (model Unicam SP 90), in the hair of 200 persons residing in the immediate vicinity (within a distance of 5 km) of a lead smeltery and in a control group of 200 persons living at a distance greater than 10 km from the main air pollution source. Statistically significant differences in the content of the metals were found, the probability range being 0.05-0.01. The concentration of lead, cadmium, copper and zinc in permanent teeth was also analysed in relation to the distance of the residence from the lead smeltery in a group of 111 persons living 1-5 km from it and in 23 persons living in the area 20 to 30 km away. The established differences were statistically significant for all analysed metals with the exception of zinc.Autori iznose rezultate merenja sadržaja olova, kadmija, bakra i cinka u 200 uzoraka kose muÅ”karaca i žena koji žive u blizini topionice olova i u uzorcima kose jednakog broja kontrolnih osoba koje žive daleko od topionice olova. Olovo, kadmij, bakar i cink određivani su atomskom apsorpcijskom spektrofotometrijom. Nađene su značajne razlike u koncentraciji ispitivanih metala između eksponirane i kontrolne skupine (p<0,05 i p<0,01). Koncentracije olova, kadmija, bakra i cinka merene su i u trajnim zubima 111 osoba koje žive u blizini topionice kao i u zubima 23 kontrolne osobe koje žive daleko od topionice. I u ovim su uzorcima utvrđene statistički značajne razlike u koncentracijama svih metala osim cinka između dviju ispitivanih grupa

    Uticaj sistematskih faktora na mlečnost krava Simentalske rase u celim laktacijama

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    The effect of systematic factors on production traits over complete lactations was investigated in 2,805 Simmental cows born in 1982 and onwards. The cows were housed at three farms in different areas: at the Zlatiborski Suvati dairy farm, Zlatibor, at the Dobricevo Agricultural Farm, Cuprija and at private farms in the region of Kotraze. The systematic factors (farm, calving season, lactation groups, group (year x season of birth), farm x calving season and farm x lactation group interactions) and age at first conception had statistically highly significant (P (lt) 0.001) effects on all complete lactation traits, with the exception of the effect of calving season on complete lactation duration (P (lt) 0.05) and milk-fat content (P>0.05). No statistically significant effect was produced by age at first conception on complete lactation duration and milk-fat content (P>0.05). Determination coefficients ranged from 0.100 in complete lactation duration to 0.361 in milk-fat content.Ispitivanje uticaja sistematskih faktora na ispoljenost proizvodnih osobina celih laktacija obavljeno je kod 2805 krava simentalske rase rođenih od 1982. godine pa na dalje. Krave su smeÅ”tene na tri farme, odnosno područja: farmi muznih krava 'Zlatiborski suvati' na Zlatiboru, Poljoprivrednom dobru Dobričevo u Ćupriji i području Kotraže na individualnim gazdinstvima. Sistematski faktori (farma, sezona telenja, grupe laktacija, grupa (godina x sezona rođenja), interakcije farma x sezona telenja i farma x grupe laktacija) i uzrast pri prvoj oplodnji statistički su vrlo visoko značajano (P (lt) 0.001) uticali na sve osobine punih laktacija, izuzimajući uticaj sezone telenja na trajanje punih laktacija (P (lt) 0.05) i sadržaj mlečne masti (P>0.05). Uzrast pri prvoj oplodnji nije statistički značajno uticao na trajanje celih laktacija i sadržaj mlečne masti u njima (P>0.05). Koeficijenti determinacije kretali su se od 0.100 kod trajanja celih laktacija do 0.361 kod sadržaja mlečne masti

    Korelaciona analiza povezanosti proizvodnih osobina kroz tri generacije krava simentalske rase

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    The relationship between milk production traits over whole lactations was evaluated across three generations of Simmental cows, i.e. between daughters, dams and grand dams, by a phenotypic regression analysis with whole lactation traits in the daughter generation being used as the dependent variables (x1), and those in the dam and grand dam generations being used as the independent variables (x2 and x3). The results were obtained from a sample of 1170 daughters and as many dams and grand dams. The significance of the partial regression coefficients b2 and b3 was separately evaluated by a t-test. An analysis of variance was used to estimate the significance of the simultaneous effect of the production traits of dams and grand dams on the milk production achieved in the daughter generation. The calculated value of the partial regression coefficients for the whole lactation production traits across three generations (grand dams, dams and daughters) and their statistical significances determined by the t and F tests, as well as the regression equations used, suggested that the effect of the grand dam generation on the milk production traits in granddaughters was substantially lower than the effect of dams. The calculated partial regression coefficients (b2 and b3) were positive and statistically very significant (P lt 0.01), excepting the regression coefficients b3 for lactation length and b2 for milk fat content that were not statistically significant (P>0.05). A very significant change (P lt 0.01) was observed in all production traits in the daughter generation as simultaneously affected by the traits in the dam and grand dam generations.Povezanost osobina mlečnosti u punim laktacijama analizirana je između tri generacije krava simentalske rase, odnosno između kćerki, majki i baba, fenotipskom regresionom analizom u uslovima kada su osobine punih laktacija u generaciji kćerki posmatrane kao zavisno (x1), a osobine punih laktacija u generaciji majki i baba kao nezavisno promenljive (x2 i x3). Rezultati su dobijeni na uzorku od po 1170 kćerki, majki i baba. Pojedinačno ispitivanje značajnosti delimičnih regresionih koeficijenata b2 i b3 izvrÅ”eno je t-testom, a analizom značajnosti istovremenog uticaja proizvodnih osobina majki i baba na ostvarenu proizvodnju kod kćerki izvrÅ”ena je metodom analize varijanse. Na osnovu izračunate vrednosti delimičnih regresionih koeficijenata za proizvodne osobine celih laktacija kroz tri generacije (babe, majke i kćerke) i njihove statističke značajnosti određene t i F testom, kao i jednačina regresije konstatovano je da je uticaj generacije baba na proizvodnju unuka znatno manji u odnosu na uticaj kojeg imaju majke. Svi izračunati delimični koeficijenti regresije (b2 i b3) bili su pozitivni i statistički vrlo značajni (P lt 0.01), izuzimajući koeficijent regresije b3 kod trajanja laktacije i b2 kod sadržaja mlečne masti koji nisu bili statistički značajni (P>0.05). Značajnost promena svih posmatranih proizvodnih osobina u generaciji kćerki pri istovremenom uticaju tih osobina iz generacije majki i baba bila je vrlo visoka (P lt 0.01)

    Uticaj paragenetskih faktora na reproduktivne osobine krava simentalske rase

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    The examination was made on the effect of systematic factors (parturition group, calving season, birth type, calf gender, and birth type-calf gender interaction) and age at first conception on the expression of reproductive traits (gestation length, service period, fertility intensity and calf birth weight) in 143 Simmental cows. The overall mean (Ī¼) for gestation length, service period, intercalving period and calf birth weight was 284.14 days, 153.82 days, 416.92 days and 35.40 kg, respectively. The parturition group effect on all fertility traits was highly significant (P lt 0.01). The calving season statistically significantly (P lt 0.05) affected the intercalving period and calf birth weight. Birth type induced very significantly longer gestation (P lt 0.01) and higher calf birth weight in singles (P lt 0.01) and significantly longer service period in twins (P lt 0.05). Calf gender had a very significant effect (P lt 0.01) only on calf birth weight, and the interaction between birth type and calf gender significantly affected gestation duration only (P lt 0.05). The regression effect of age at first conception on all fertility traits was not significant (P>0.05).Na ispoljenost reproduktivnih osobina (dužina bremenitosti, servis period, intenzitet plodnosti i masa teladi pri rođenju) kod 143 krave simentalske rase, ispitivan je uticaj sistematskih faktora (grupe partusa, sezone telenja, tip rođenja, pol teladi i interakcija tipa rođenja i pola teladi) i uzrasta pri prvoj oplodnji. OpÅ”ti prosek (Ī¼) za dužinu bremenitosti iznosio je 284.14 dana, servis period 153.82 dana, međutelidbeni interval 416.92 i masu teladi pri rođenju 35.40 kg. Uticaj grupe partusa na sve osobine plodnosti bio je visoko značajan (P lt 0.01). Sezona telenja statistički značajno (P lt 0.05) je uticala na međutelidbeni interval i masu teladi pri rođenju. Tip rođenja uslovio je vrlo značajno dužu bremenitost (P lt 0.01) i veću masu teladi pri rođenju kod jedinaca (P lt 0.01) i značajno duži servis period kod blizanaca (P lt 0.05). Pol teladi vrlo značajno je uticao (P lt 0.01) samo na masu teladi pri rođenju, dok je interakcija tipa rođenja i pola teladi značajno uticala samo na trajanje bremenitosti (P lt 0.05). Regresijski uticaj uzrasta pri prvoj oplodnji na sve osobine plodnosti nije bio signifikantan (P>0.05)

    Uticaj nivoa mlečnosti na osobine plodnosti krava crno bele rase

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    In this study a relationship between the milk yield and following reproduction traits: number of inseminations per conception [AIS], service period [SP], age at calving [AC], calving interval [CI] and birth weight [BW] is studied. The research involved dairy cows of European type of Black and White cattle which are being intensively improved by the genes of Holstein - Friesian breed. Mean values of general average for number of inseminations per conception, service period, age at calving, calving interval and birth weight are: 2.00; 98.78; 1088.08; 376.70 and 36.40, respectively. In general, the estimated phenotypic correlations (rp) between the milk yield over standard lactations and fertility traits were positive and unfavorable, and ranged from 0.24 for the relationship between milk yield and birth weight to 0.70 for relationship between milk yield and age at calving.U radu je ispitivan odnos između prinosa mleka i sledećih osobina plodnosti: indeks osemenjavanja [IO], servis period [SP], uzrast pri teljenju [UT], međutelidbeni interval [MI] i masa teladi pri rođenju [MTR]. Ispitivanja su se odnosila na mlečne krave evropskog tipa crno-belih goveda koje se intenzivno oplemenjuju genima holÅ”tajn-frizijske rase. Za analizu je koriŔćen Metod najmanjih kvadrata - LSMLMW (HARVEY, 1990), fiksni model. Srednje vrednosti opÅ”teg proseka za indeks osemenjavanja, servis period, uzrast pri teljenju, međutelidbeni interval i masu teladi pri rođenju su: 2,00; 98,78; 1088,08 ; 376,70 i 36,40, respektivno. Procenjene fenotipske korelacije (rp) između prinosa mleka i osobina plodnosti generalno su bile pozitivne i nepovoljne, i imale su vrednosti od 0,24 za odnos između prinosa mleka i masu teladi pri rođenju do 0,70 za odnos između prinosa mleka i uzrasta pri teljenju

    Study of Collinear Collision in Impulsive Model

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    Exact quantum solution of the collinear collision problem is found in the impulsive model. The transition probabilities compare well with those for real systems, except when multiple collisions become important

    Axial light emission and Ar metastable densities in a parallel plate dc micro discharge in steady state and transient regimes

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    Axial emission profiles in a parallel plate dc micro discharge (feedgas: argon; discharge gap d=1mm; pressure p=10Torr) were studied by means of time resolved imaging with a fast ICCD camera. Additionally, volt-ampere (V-A) characteristics were recorded and Ar* metastable densities were measured by tunable diode laser absorption spectroscopy (TDLAS). Axial emission profiles in the steady state regime are similar to corresponding profiles in standard size discharges (d=1cm, p=1Torr). For some discharge conditions relaxation oscillations are present when the micro discharge switches periodically between low current Townsend-like mode and normal glow. At the same time the axial emission profile shows transient behavior, starting with peak distribution at the anode, which gradually moves towards the cathode during the normal glow. The development of argon metastable densities highly correlates with the oscillating discharge current. Gas temperatures in the low current Townsend-like mode (T= 320-400K) and the high current glow mode (T=469-526K) were determined by the broadening of the recorded spectral profiles as a function of the discharge current.Comment: submitted to Plasma Sources Sci. Techno

    Sustainable Tourism as a Part of Comprehensive Environmental Monitoring. A Study of Serbia

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    The sustainable tourism comprises the freedom of tourist travelling, satisfying the economic, social and aesthetic needs, with the preservation of the characteristics of the natural and social environment and the cultural and historical heritage. It should optimize the usage of environmental resources that make the key element of tourism development, maintaining the essential ecologic processes and helping in heritage preservation, and providing the sustainable long-term business.As the consequences of the anthropogenic activities are obvious in the deterioration of the environment quality, the analysis of the status and influence on the environment and humans, as well as on the flora and fauna, must be under constant monitoring. The aim is to detect the corresponding influences and changes and to establish their cause. The paper approaches the structure, the processes and the application of the comprehensive monitoring of the environment with the aim of creating a database for the development of sustainable tourism in Serbia. The risk of the anthropogenic pollution of the environment, as a result of tourist activities, and monitoring of these activities in order to create a database for a planned and coordinated activity of tourism development will be considered in detail
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