A Factor Model of the Relationship between Stream Sediment Geochemistry and Adjacent Drainage Basin Lithology, Medvednica Mt., Croatia

A mathematical model is constructed to relate the geochemical composition of recent stream material in a number of catchments on Medvednica Mt. to a broadely defined bedrock lithology which represents the parent material for the former. It is a system based factor model, which synthesizes eight lithological and 25 geochemical variables (major, minor and trace elements), reducing their relationships to six geologically meaningful factors. Five of these divulged a definite relationship between geochemistry and lithology. These are labelled as follows: factor of metamorphic rocks; factor of igneous rocks; factor of Tertiary carbonate rocks; factor of parametamorphic rocks and factor of Mesozoic carbonate rocks. Two lithologies; the Mesozoic clastic rocks and Quaternary sediments showed no clear association to any of the factors. Alternatively, one of the factors (F2) can be identified as “non-lithologic” indicating other, perhaps anthropogenic, contributions to the stream sediment geochemical composition

Pozadinski geokemijski šum u tlima Istre

The geochemical background is postulated for two major groups of soils of the Istrian Peninsula, depending on the type of bedrock, or parent material as one of the main soil-forming factors. An effort is made to combine conceptual fundamentals of non-linear dynamic theory with the principles, methods and practical application of basic statistics in order to elucidate the nature and origin of elemental subpopulations hidden in the original geochemical data of Istrian topsoils. In this sense, the 4σ-outlier test and iterative 2σ-statistical technique are utilized, by which the outliers and anomalous values are removed from the total data set and assigned to the consequences of non-linear system dynamics, which prevents the development of a simple cause-and-effect relationship between geochemical variables. The geochemical background is then defined as the normal range of data of the remaining data set. As confirmed by the study, the carbonate-derived soils have a higher natural or geogenic baseline and are also more strongly loaded with heavy metals and other trace elements, in some places critically. On the other hand, flysch-derived soils, except for higher Ca contents, are actually depleted in many elements and also devoid of outliers. Such behaviour implies »dilution« due to the characteristic nature of the weathering of the underlying parent material and other soil-forming processes controlling their fate. In a general sense, the character of the probability distribution curves among chemical elements in the topsoil (or soils in general) can be used as reliable indicator of their evolutionary trends, that is, their enrichment or depletion, or, as regards the geochemical background, the equilibrium between the two, which in the case studied depends principally upon the contrasting Istrian bedrock lithology.U radu je razmatran geokemijski šum zasebno za dvije skupine tala na Istarskom poluotoku, ovisno o tipu geološke podloge, odnosno ishodišnog materijala kao jednog od glavnih čimbenika u razvitku tla. Povezana je teorija nelinearnih dinamičkih sustava s načelima, metodama i praktičnom primjenom elementarne statistike s ciljem da se razjasni priroda i porijeklo elementnih subpopulacija skrivenih u izvornim geokemijskim podacima površinskog horizonta istarskih tala. U tu svrhu korištene su statističke metode – 4σ-test za određivanje ekstremnih vrijednosti i 2σ-metoda iteracije – kojima su ekstremi i anomalne vrijednosti odvojeni od glavnog skupa podataka i pripisani posljedicama nelinearne sistemske dinamike koje su brana uspostavi jednostavnih, uzročno-posljedičnih odnosa među geokemijskim varijablama. U skladu s navedenim, geokemijski šum je određen kao raspon normalnih vrijednosti reduciranog skupa podataka nastalog nakon oba statistička postupka. Pokazalo se da tla razvijena na karbonatnim stijenama imaju višu prirodnu razinu kemijskih elemenata, a također sadrže i veću koncentraciju teških metala i elemenata u tragovima koja je na pojedinim lokacijama i ekstremno visoka. S druge strane, tla razvijena na flišu, s izuzetkom povišenog sadržaja kalcija, u stvarnosti su siromašnija sadržajem većine elemenata i ne sadrže ekstremnih vrijednosti. Takvo ponašanje ukazuje na »razrjeđenje« zbog karakteristične prirode trošenja ishodišnog materijala i drugih čimbenika koji utječu na raspodjelu elemenata u površinskom horizontu tla. U općem slučaju, karakter krivulje statističke distribucije elemenata kemijskih elemenata u površinskom horizontu (i u tlu općenito) može se uzeti kao pouzdan pokazatelj evolucijskih trendova, odnosno obogaćenja ili osiromašenja pojedinim elementima ili, kad je riječ o geokemijskom šumu, ravnoteže među ovim procesima. Kod tala na području Istre na ove odnose primarno utječe izrazita razlika u karakteru geološke podloge

Search of low-dimensional magnetics on the basis of structural data: spin-1/2 antiferromagnetic zigzag chain compounds In2VO5, beta-Sr(VOAsO4)2,(NH4,K)2VOF4 and alpha-ZnV3O8

A new technique for searching low-dimensional compounds on the basis of structural data is presented. The sign and strength of all magnetic couplings at distances up to 12 A in five predicted new antiferromagnetic zigzag spin-1/2 chain compounds In2VO5, beta-Sr(VOAsO4)2, (NH4)2VOF4, K2VOF4 and alpha-ZnV3O8 were calculated. It was stated that in the compound In2VO5 zigzag spin chains are frustrated, since the ratio (J2/J1) of competing antiferromagnetic (AF) nearest- (J1) and AF next-to-nearest-neighbour (J2) couplings is equal to 1.68 that exceeds the Majumdar-Ghosh point by 1/2. In other compounds the zigzag spin chains are AF magnetically ordered single chains as value of ratios J2/J1 is close to zero. The interchain couplings were analyzed in detail.Comment: 14 pages, 6 figure, 1 table, minor change

The impact of temporal variability of biochemical markers PAPP-A and free β-hCG on the specificity of the first-trimester Down syndrome screening: a Croatian retrospective study

<p>Abstract</p> <p>Background</p> <p>The variability of maternal serum biochemical markers for Down syndrome, free β-hCG and PAPP-A can have a different impact on false-positive rates between the 10+0 and 13+6 week of gestation. The study population comprised 2883 unaffected, singleton, spontaneously conceived pregnancies in Croatian women, who delivered apparently healthy child at term. Women were separated in 4 groups, dependently on the gestational week when the analyses of biochemical markers were performed. The concentrations of free β-hCG and PAPP-A in maternal serum were determined by solid-phase, enzyme-labeled chemiluminiscent immunometric assay (Siemens Immulite). Concentrations were converted to MoMs, according to centre-specific weighted regression median curves for both markers in unaffected pregnancies. The individual risks for trisomies 21, 18 and 13 were computed by Prisca 4.0 software.</p> <p>Findings</p> <p>There were no significant differences between the sub-groups, regarding maternal age, maternal weight and the proportion of smokers. The difference in log₁₀MoM free β-hCG values, between the 11^thand 12^thgestational week, was significant (p = 0.002). The difference in log₁₀MoM PAPP-A values between the 11^thand 12^th, and between 12^thand 13^thweek of gestation was significant (p = 0.006 and p = 0.003, respectively). False-positive rates of biochemical risk for trisomies were 16.1% before the 11^thweek, 12.8% in week 12^th, 11.9% in week 13^thand 9.9% after week 13^th. The differences were not statistically significant.</p> <p>Conclusions</p> <p>Biochemical markers (log₁₀MoMs) showed gestation related variations in the first-trimester unaffected pregnancies, although the variations could not be attributed either to the inaccuracy of analytical procedures or to the inappropriately settled curves of median values for the first-trimester biochemical markers.</p

Pozadinski geokemijski šum u tlima Istre

The geochemical background is postulated for two major groups of soils of the Istrian Peninsula, depending on the type of bedrock, or parent material as one of the main soil-forming factors. An effort is made to combine conceptual fundamentals of non-linear dynamic theory with the principles, methods and practical application of basic statistics in order to elucidate the nature and origin of elemental subpopulations hidden in the original geochemical data of Istrian topsoils. In this sense, the 4σ-outlier test and iterative 2σ-statistical technique are utilized, by which the outliers and anomalous values are removed from the total data set and assigned to the consequences of non-linear system dynamics, which prevents the development of a simple cause-and-effect relationship between geochemical variables. The geochemical background is then defined as the normal range of data of the remaining data set. As confirmed by the study, the carbonate-derived soils have a higher natural or geogenic baseline and are also more strongly loaded with heavy metals and other trace elements, in some places critically. On the other hand, flysch-derived soils, except for higher Ca contents, are actually depleted in many elements and also devoid of outliers. Such behaviour implies »dilution« due to the characteristic nature of the weathering of the underlying parent material and other soil-forming processes controlling their fate. In a general sense, the character of the probability distribution curves among chemical elements in the topsoil (or soils in general) can be used as reliable indicator of their evolutionary trends, that is, their enrichment or depletion, or, as regards the geochemical background, the equilibrium between the two, which in the case studied depends principally upon the contrasting Istrian bedrock lithology.U radu je razmatran geokemijski šum zasebno za dvije skupine tala na Istarskom poluotoku, ovisno o tipu geološke podloge, odnosno ishodišnog materijala kao jednog od glavnih čimbenika u razvitku tla. Povezana je teorija nelinearnih dinamičkih sustava s načelima, metodama i praktičnom primjenom elementarne statistike s ciljem da se razjasni priroda i porijeklo elementnih subpopulacija skrivenih u izvornim geokemijskim podacima površinskog horizonta istarskih tala. U tu svrhu korištene su statističke metode – 4σ-test za određivanje ekstremnih vrijednosti i 2σ-metoda iteracije – kojima su ekstremi i anomalne vrijednosti odvojeni od glavnog skupa podataka i pripisani posljedicama nelinearne sistemske dinamike koje su brana uspostavi jednostavnih, uzročno-posljedičnih odnosa među geokemijskim varijablama. U skladu s navedenim, geokemijski šum je određen kao raspon normalnih vrijednosti reduciranog skupa podataka nastalog nakon oba statistička postupka. Pokazalo se da tla razvijena na karbonatnim stijenama imaju višu prirodnu razinu kemijskih elemenata, a također sadrže i veću koncentraciju teških metala i elemenata u tragovima koja je na pojedinim lokacijama i ekstremno visoka. S druge strane, tla razvijena na flišu, s izuzetkom povišenog sadržaja kalcija, u stvarnosti su siromašnija sadržajem većine elemenata i ne sadrže ekstremnih vrijednosti. Takvo ponašanje ukazuje na »razrjeđenje« zbog karakteristične prirode trošenja ishodišnog materijala i drugih čimbenika koji utječu na raspodjelu elemenata u površinskom horizontu tla. U općem slučaju, karakter krivulje statističke distribucije elemenata kemijskih elemenata u površinskom horizontu (i u tlu općenito) može se uzeti kao pouzdan pokazatelj evolucijskih trendova, odnosno obogaćenja ili osiromašenja pojedinim elementima ili, kad je riječ o geokemijskom šumu, ravnoteže među ovim procesima. Kod tala na području Istre na ove odnose primarno utječe izrazita razlika u karakteru geološke podloge