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15 páginas, 7 figuras, 3 tablas, [EN] The Late Devonian - Early Carboniferous St. Mary's Basin in the Canadian Appalachians consists of Horton Group fluviatile and lacustrine clastic rocks. The basin occurs along the boundary between the Avalon and Meguma terranes and developed during coeval dextral shear along that boundary. X-ray diffraction reveals that the rocks contain ubiquitous quartz, K-white mica, and albite; illite-smectite mixed layers and chlorite are very common and Na-K mica, kaolinite, chlorite-smectite mixed layers, K-feldspar, berthierine, and rutile occur in some samples. Crystal-chemical parameters of white mica indicate the pressure and temperature of mineral growth and discriminate between diagenetic, anchizone, and low-grade metamorphic processes. Kübler index values measured in the 5 Å peak and the presence of chlorite-mica stacks are indicative of high-anchizone-epizone grades, with a crystallinity (crystal size and number of defects) that increases towards the Chedabucto Fault, which defines the northern margin of the basin. Kübler index values measured in the 10 Å peak indicate that a late fluid-rich event could have produced the observed illite-smectite mixed layers. The overall clay-mineral content and the b-cell dimension of the K-white micas are typical of postdepositional evolution in extensional sedimentary basins with high heat flow (>35°C/km). Taken together, our data record two superposed events related to deformation along the basin margins and coeval regional fluid flow, in which retrograde reactions at temperature T < 200°C were superimposed on a pre-existing prograde assemblage typical of high-anchizone - lower greenschist-facies conditions (T> 300°C). Regional syntheses indicate that this fluid flow may have occurred during episodes of Late Carboniferous dextral shear along the Avalon-Meguma terrane boundary., [FR]Le bassin St. Mary's (Dévonien tardif - Carbonifère précoce) dans les Appalaches canadiennes est composé de roches clastiques fluviatiles et lacustres du Groupe de Horton. Le bassin se situe le long de la bordure entre les terranes d'Avalon et de Meguma et il s'est développé le long de cette bordure durant une période de cisaillement dextre de même âge. Des diffractions aux rayons X révèlent que les roches contiennent du quartz, du mica blanc (K) et de l'albite de manière généralisée; des couches d'un mélange illite-smectite ainsi que de la chlorite sont très fréquentes et on retrouve, dans quelques échantillons, du mica Na-K, de la kaolinite, des couches d'un mélange chlorite-smectite, du feldspath K, de la berthiérine et du rutile. Les paramètres chimiques de cristaux du mica blanc indiquent la pression et la température de la croissance minérale et distinguent entre les processus diagénétiques, d'anchizone et un métamorphisme de faible intensité. Les valeurs de l'indice de Kübler mesurées dans un pic de 5Å et la présence d'éperons chlorite-mica indiquent des degrés métamorphiques élevés, d'anchizone supérieur à épizone, avec une cristallinité (taille du cristal et nombre de défauts) qui augmente en direction de la faille Chedabucto, laquelle forme la limite nord du bassin. Les valeurs de l'indice de Kübler mesurées dans un pic de 10Å indiquent qu'un événement tardif, riche en fluides, pourrait avoir produit les couches mélangées illite-smectite observées., Proyecto de investigación GL 2007-66744 del Ministerio de Ciencia y Tecnología y Grupo de Investigación RNM-179 y RNM-325 de la Junta de Andalucía.

15 páginas, 10 figuras, 3 tablas, Variations in clay–mineral assemblages in ancient continental deposits are frequently used to reconstruct past climate changes. In active settings, volcanic events can supply highly labile volcaniclastic material, which can easily be transformed into smectite via diagenesis, which can produce a noticeable footprint in clay–mineral assemblages. Southern Central Andean foreland deposits are appropriate case studies to ascertain whether the climatic signal was preserved in the clay assemblages of their fine-grained sediments as tectonic uplift, volcanism, and sedimentation have been interacting since the Cretaceous. We have studied a 1400-m-thick coarsening-upward Palaeogene succession of the Tin Tin basin (northern Calchaquí Valley, Argentina), applying X-ray diffraction (XRD), electron microscopy, and detailed sedimentary facies analysis with the aim of comparing tendencies in the vertical fluctuations of clay minerals with evidence from sedimentological facies. Illite–muscovite plus smectite account for 78% to 100% of the clay minerals in the fine fraction, with kaolinite and chlorite in subordinate amounts. The vertical variation of sedimentary settings from an overbank/lacustrine domain to fluvial braided plains and an aeolian dune field suggests a gradual increase in aridity upsection. However, smectite abundances do not show a gradual decreasing trend compatible with progressively lower hydrolyzing conditions; their relative abundances vary widely throughout the section, depicting pulse-like, abrupt fluctuations. Despite the absence of field evidence for volcanic influence, several indications of volcanic and volcaniclastic material have been found under scanning electron microscopy (SEM) in levels with high smectite abundances from the middle to the top of the succession. They include quartz crystals showing embayments and skeletal forms, with smectite filling the voids, microcrystalline silica, as well as heulandite crystals in close association with authigenic smectite. The XRD analyses of these levels evidence well-crystallized smectite, which is characteristic of a volcaniclastic origin. Therefore, the increase in smectite abundance in these beds reflects a significant volcaniclastic contribution, which is also evidenced by a centimetre-thick ash layer topward in the sequence. The only smectite-rich level near the base of the Tin Tin section also contains well-crystallized smectite associated with heulandite, thus probably evidencing volcaniclastic input. We infer that most of the smectite in these sediments formed during early diagenesis, probably through the dissolution of labile tuffaceous material. Textural and morphological analysis by SEM is essential to determine whether clay–mineral assemblages could be interpreted in terms of palaeoclimate., Este trabajo ha sido parcialmente financiado por CONICET-PIP0781 y ANCyT-PICT 2006-381 y el Proyecto de Investigación CGL2007-66744-C02-01(Ministerio de Ciencia y Tecnología). La estancia de M. do Campo en la Universidad de Granada y el trabajo de campo de Fernando Nieto en Argentina ha estado financiado por el Proyecto AECI A/5120/06 y A/7712/07.

9 páginas, 5 figuras, 3 tablas, The mechanism for the kaolinization of smectite is extremely complex. The purpose of this study was to explore this mechanism by providing more microscopic information about kaolinite-smectite (K-S) intermediate phases. Crystal-chemical changes were investigated and integrated in a model of the transformation mechanism. Eight K-S samples from three localities, derived from volcanic ash beds, were studied using transmission and analytical electron microscopy (TEM, AEM) and high-resolution TEM (HRTEM). The study completes a previous investigation, using several analytical techniques. The samples cover the range of K-S composition available from the previously studied sample set. Analysis by TEM indicated the preservation of particle morphology throughout the process. Most K-S particles had anhedral, smectite-like morphology, and only the most kaolinitic specimen revealed the coexistence of anhedral and euhedral, hexagonal particles. Analytical electron microscopy showed large chemical variations within samples, corresponding to various degrees of smectite kaolinization. Comparison of chemical results (Si/Al) and d060 values (proxy for octahedral composition) with the extent of kaolinization from thermogravimetry (TG) indicates that chemical changes in the octahedral sheet occur mainly when the proportion of kaolinite is 40–70%. The results above are consistent with kaolinization occurring via layer-by-layer transformation through the progressive loss of individual tetrahedral sheets in smectite layers and subsequent chemical changes in the octahedral sheet. Such a mechanism would produce the results observed in this study: (1) most particles preserve their original morphology; (2) significant variation in terms of the extent of transformation of particles within samples, and (3) formation of crystal structures intermediate between those of smectite and kaolinite, with parts of the tetrahedral sheets missing (kaolinite-like patches). Such structures become least stable at kaolinite ~50%, when the perimeter of the kaolinite-like patches is largest and chemical changes in the octahedral sheet can occur more easily. Kaolinite layers could not be resolved by HRTEM in most cases and showed lattice fringes corresponding to superstructures. A model was established to quantify kaolinite and smectite layers in the HRTEM images with results which matched TG-derived values., Apoyo financiero de la Real Sociedad de la OTAN (subvención 15144/02B/TB), EPSRC (subvención GR/S59772/01), el Programa de Becas Marie Curie (contrato MEIF-CT-2.003-501.678), y el Ministerio de Educación y Ciencia (Proyecto de Investigación CGL2007-66744)

8 páginas, 6 figuras, 7 tablas., Lattice parameters for gold nanocrystals, quartz, and vesuvianite have been determined by electron diffraction in routine transmission electron microscopy (TEM) work, with precision and accuracy near to 0.1%, after correction for elliptical distortion. The distortion, measured in three different microscopes, is constant for each microscope and may be easily eliminated. Variable camera constants have been avoided by positioning the oriented specimen on the eucentric plane and using parallel illumination. The current flowing in the first intermediate lens was kept fixed, assuring constant conditions of the TEM projecting system, with no further diffraction focus applied. Application of this method to micas from metamorphic rocks produced deviations between measured and expected values up to 0.8%. Although easy species distinction is still possible, minor crystal chemical differences within the sample may be lost. Likely causes of these deviations are the possible heterogeneous samples, as well as beam damage leading to cation loss with subsequent variation in basal spacings., M.M. is grateful to the Secretaría de Estado de Universidades y Investigación del Ministerio de Educacion y Ciencia de España for the invitation to spend a sabbatical term at Universidad de Granada (Grant SAB2005-0191), where this study originated. F.N. is grateful to the financial support by Research Project no. CGL2007-66744 (Ministerio de Educacion y Ciencia de España).

12 páginas, 4 figuras, 2 tablas, Minerals with biotite-like optical properties occur in the Nevado-Filabride micaschists. The grains are highly pleochroic, variable in colour from light yellow to deep red, and strongly recall the descriptions given for "oxychlorite". Based on X-ray powder diffraction, microprobe analysis and transmission electron microscopy, two main types are recognized in optically similar grains: 1) Those consisting of a chlorite matrix interleaved with approximately 5 % by volume of very thin biotite lamellae. 2) Those consisting of a chlorite-like, hydrated material that produces irrational 16-16.5 angstrom spacings in the X-ray diffraction pattern. These values progressively decrease upon heating. This material gives microprobe analyses close to coexisting chlorite, but shows systematically lower oxide sums, of the order of 79-85 wt.%. Wavy rather than straight lattice fringes are obtained on these grains. Lamellae of haematite, or of a precursor of haematite, a few hundred angstrom in thickness and with granular appearance, may occur interleaved with the 16 angstrom material. The 16 angstrom hydrated chlorite is a retrograde alteration product which is supposed to have been derived from the grains consisting of chlorite-mica association. Low temperature reactions occurred during the very late evolution stage of the Veleta unit, producing the hydration of chlorite and alteration of plagioclase, chloritoid and garnet. These reactions occurred during the recent, relatively rapid uplift of the Veleta rocks.

Oxygen (O2) transport was assessed through the affinity between O2 and hemoglobin (Hb) in 123 newborns of 28 to 40 week gestational ge, with a minimum of 9 newborns for each gestational age group (see table). In order to assess the O2-Hb affinity, we studied the correlation between the pO2 and the Hb saturation for each gestational age, obtaining estimates of the oxy-hemoglobin dissociation curves corresponding to each gestational age (see fig. 3). The pO2 levels corresponding to the 50% saturation (P50) for each gestational age were estimated from there. All newborns were from single vaginal deliveries with no fetal distress before birth and with an adequate weight for gestational age. The latter was calculated according to the date of the last menstrual period (78% of the cases), echography (10.6% of the cases) or neonatal physical exam (11.4% of the cases). A P50 vs. gestational age linear regression showed a high determination rate (r2 = 0.957, p less than 0.00001) (see fig. 2) which supports the hypothesis of the P50 linear growth; decrease in the Hb-O2 affinity with increasive gestational age (Hb-O2 affinity is different in newborns of different gestational ages). With these results one may conclude that the Hb-O2 uptake varies according to gestational age (P50 changes linearly as gestational age increases) and that a single measurement of pO2 in a newborns, blood does not accurately evaluate the amount of O2 that is transported to the tissues, because the transport capacity depends, among other factors, upon gestational age. The Hb saturation better represents the amount of O2 that can get to the cell level.(ABSTRACT TRUNCATED AT 250 WORDS)

Dolerites from the Sierra de San Pedro (Betic Cordillera, southern Spain) develop three main types of microsystems during hydrothermal alteration: (1) centimetre-sized veins cross-cutting the dolerites; (2) microfractures in feldspar and diopside grains; and (3) alterations involving primary-igneous mafic phyllosilicate grains. The vein and microfracture sites developed alteration assemblages of randomly oriented smectites (saponite and beidellite) and halloysite. At these sites, the alteration mechanism was governed by complete dissolution of the parent material with subsequent crystallization of the products, with no parent-mineral crystallographic control. Pseudomorphed mafic phyllosilicate sites are characterized by oriented complex mineral assemblages made of chlorite, chlorite/smectite mixed layers, corrensite, saponite and relicts of biotite. These assemblages formed during the initial high-temperature stage of the hydrothermal process. In these microsites, the alteration sequence was controlled by the parent-mineral structure and chemistry, with products determined by structural relations with the parent phyllosilicate. Alteration of one phyllosilicate to the next most stable proceeds via interstratification of the parent and product phyllosilicates.

22 pages, 9 figures, 1 table., The Palaeogene Maíz Gordo Formation is one of the main lacustrine events recorded in northwestern Argentina. It consists of sandstone, mudstone, and limestone beds 200 m thick, deposited in a brackish–alkaline lake and braided alluvial systems. The Maíz Gordo Lake evolved mainly as a closed system, with brief periods as an open one. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study samples from seven sites, corresponding respectively to proximal, intermediate, and transitional positions of the fluvial environment and marginal and inner-lake environment, focusing on the clay mineralogy and analcime formation. The basinward zonation of diagenetic minerals identified in the Maíz Gordo Lake was: mordenite → analcime → K-feldspar. Although not a typical zonation of saline–alkaline lakes, it does indicate an increase in salinity and alkalinity towards the centre. In proximal fluvial settings, smectite predominates at the base of the sequence, with scarce kaolinite. Towards the top, a striking increase in kaolinite content suggests a change from a relatively arid climate with alternating humid and dry seasons, towards a warm and humid climate. Kaolinite content clearly decreases in a basinward direction. Such a variation is attributable to changes in hydro-geochemistry, denoting the progressive influence of the brackish and alkaline lake water on interstitial pores. SEM images of intermediate fluvial samples reveal authigenesis of illite at the expense of kaolinite booklets. In littoral and inner-lake settings the clay fraction is composed of muscovite, sometimes with subordinate smectite. Analcime occurs in variable amounts in all sedimentary facies, in rock pores or filling veins. It forms subhedral square to hexagonal, or anhedral rounded crystals, denoting that they coarsened at low to moderate degrees of supersaturation. Although the mordenite identified in a fluvial level would have been the precursor of analcime in the Maíz Gordo Basin, no textural evidence of analcime formation through replacement of mordenite or other precursor zeolite was found. Hence it is more probable that analcime formation took place by direct authigenic precipitation or through the reaction between interstitial brines and clay minerals or plagioclase., The authors are grateful to Sheilagh Douma (Journal Manager) and two anonymous reviewers for their valuable and constructive comments. We thank Alicia Gómez Segura (Centro de Instrumentación Científica, University of Granada) for her help with the SEM. The stay ofM. Do Campo at the University of Granada was supported by an AECI fellowship awarded in 2003 (MAE-AECI programme). This work was partially financed by CONICET-PEI 6091 and ANCyT – PICT 12419 grants and Research Project BTE2003-07867 (Spanish Ministry of Science and Technology). This paper is a contribution to INCE and IBIGEO(FCN—Universidad de Salta).Our thanks to Christine Laurin for revising the English.

Laser Doppler flux signals show temporal fluctuations caused by physiological phenomena like heartbeat, respiration, and local variation of vascular tonus, vasomotion. This study investigates the influence of fiber arrangement, equipment and two probe locations on the variations in laser Doppler flux signals in five frequency bands in the absence of provocations. Two probes with detecting optical fibers at several distances from the illuminating source were used, as well as instruments from two manufacturers. The results show that normalization of the filtered flux signals with the mean flux leads to an enormous decrease of the influence of fiber distance. The difference between instruments is small after normalization. Some influence of probe location remains after normalization. Development of a standard method for normalization of the variations in laser Doppler signals is recommended.

This paper estimates a single-equation model to analyse the main explanatory factors behind changes in Spanish household credit, considering that the behaviour of its determinants is exogenous. According to the evidence reported, household borrowing is determined in the long run by real spending, gross wealth and the repayment term for outstanding credits, which have a positive influence, and by the cost of loans and the unemployment rate, the effect of which is of a negative sign. Developments in the short run are influenced by changes in long-term interest rates and in employment. The evidence offered suggests that, in general terms, the financing received by households over the period analysed is in line with what may be inferred from its determinants; however, the high volume of debt incurred entails greater exposure of the sector to unexpected changes in its income, in its wealth or in the cost of borrowing, especially in a setting in which floating-rate loans are increasingly significant.

The effects of the opiates morphine and morphine-6-glucuronide (M6G), the μ opioid receptor specific antagonist D-Phe-Cys-Tyr-D-Trp-Om-Thr-Pen-Thr-NH2 (CTOP), and the general opiate antagonist naloxone on the latency of response to thermal stimulation were determined in the parasitic nematode Ascaris suum. Thermal detection and avoidance behaviors of the worms were evaluated with a tail flick analgesia meter using a modification of a technique employed for nociception experiments in rodents. Morphine and M6G were shown to have a dose dependent analgesic effect on A. suum's latency of response to heat with morphine being the most potent. The analgesic effect of morphine was reversed by naloxone but not CTOP. Neither naloxone nor CTOP was able to block the analgesia of M6G. CTOP but not naloxone had significant analgesic effects on its own. These findings are generally consistent with previous results on the effects of opiates and nitric oxide release from A. suum tissue. Apparently these nematodes possess opioid receptors that effect nociception.

Occupational exposure to Hepatitis C virus is an area of growing concern due to a lack of prophylaxis and limited knowledge regarding prevalence in hospital environment. Between 1999 and 2003, a total of 128 occupational exposures to this virus were registered in Diego Paroissien Hospital, eight of which led to hepatitis (6.3%) and one case to serum conversion (0.8%). Currently there is no preventive therapy and great interest is focused on acute infection therapy the effectiveness of which is still controversial. This study reinforces the fact that adherence to the Universal Precautions is still the most important preventive measure for health care workers, and the most cost beneficial.

En este trabajo se estima un modelo para analizar los determinantes de la financiación de las sociedades no financieras españolas a nivel agregado. Los resultados muestran que la financiación depende, en el largo plazo, positivamente del nivel de actividad económica y negativamente de los tipos de interés. La elasticidad a la variable de escala se encuentra en el rango de valores estimados para otros países, mientras que la semielasticidad al tipo de interés resulta ser relativamente elevada. En el corto plazo, además, se obtiene una relación negativa con los beneficios de las empresas y con la evolución de los mercados de renta variable. Estos resultados apuntan a que el crecimiento de la financiación de las sociedades en los últimos años está en línea con la evolución de sus determinantes de largo plazo, si bien el aumento en los niveles de endeudamiento supone una mayor exposición del sector a variaciones inesperadas en los resultados económicos y en el coste de los fondos.

Mica-chlorite mixed-layering was identified by X-ray diffraction (XRD) as a major or subordinate constituent in several slates of the Puncoviscana Formation from Sierra de Mojotoro (Eastern Cordillera, NW Argentina). In order to determine the crystallochemical characteristics of these mixed-layered sequences and interpret their petrological meaning, anchizonal slate P90 was chosen for TEM observations. In this slate, dioctahedral mica and chlorite form interleaved phyllosilicate grains (IPG) or stacks, up to 110 µm long, preferentially oriented with (001) planes at a high angle to the slaty cleavage but also oblique to S0. In agreement with XRD results, the main phyllosilicates identified by transmission electron microscopy (TEM) were dioctahedral mica and random mixed-layer muscovite-chlorite, with chlorite in subordinate amounts and scarce smectite. In the lattice-fringe images of mixed-layer packets, a sequence of irregular stacking that produced apparent 24 Å (10 + 14) layers was observed, but it was frequently possible to distinguish the 10 Å layers from adjacent 14 Å layers. In nearly all packets, 14 Å layers prevail, exhibiting 14 Å :10 Å ratios between 1:1 and 3:1. Some elongated lenticular fissures which are probably a consequence of layer collapse caused by the TEM vacuum were identified in these packets. The straight, continuous appearance of lattice fringes plus the scarce evidence of collapsed layers identified suggest that these packets correspond principally to mixed-layer muscovite-chlorite, which is confirmed by analytical electron microscopy analyses. However, smectite-like layers are probably the third component of some of these mixed-layer sequences, which may account for their high Si and low (Fe + Mg) contents, their low interlayer charge in relation to theoretical interlayer muscovite-chlorite, and for the presence of Ca in the interlayer site. Textural relationships between chlorite and muscovite packets in IPG along with the observed transformations from 14 Å to 10 Å along the layer, is compatible with a prograde metamorphic replacement of chlorite in stacks by dioctahedral mica layers, probably in the presence of an aqueous fluid.

Pelitic and basic rocks occurring within prograde sequences in Portugal, Spain and Hungary have been studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The minerals formed in typical prograde reactions define the general sequences, but smectite, chlorite-smectite (corrensite) and/or berthierine were found to have replaced chlorite, whereas kaolinite and mixed-layer illite-smectite replaced illite-muscovite. Alteration occurred under conditions normally associated with diagenesis, subsequent to regional metamorphism, and we therefore refer to such processes with the term "retrograde diagenesis". In the cases studied and in other cited examples, reactions occurred on a regional basis via pervasive fluids under open-system conditions inferred to be related to tectonic stress. The observed alterations could generally not be inferred from XRD data, although the presence of pure smectite in sediments other than bentonite is suggestive of retrograde relations, especially where other minerals are consistent with a higher grade of diagenesis. Retrograde diagenesis is readily observed through imaging of textures by TEM, however. Textural features show that retrograde reactions are more common than generally assumed, and that care should be used in interpreting geological events where appropriate textural relations are not seen.

To facilitate the quantitative analysis of post-occlusive reactive hyperaemia (PORH), measured with laser-Doppler perfusion monitoring (LDPM) on extremities, we present a flow model for the dynamics of the perfusion of the tissue during PORH, based on three parameters: two time constants (/spl tau//sub 1/ and /spl tau//sub 2/) and the ratio of the maximum flux and the resting flux. With these three constants quantitative comparisons between experiments will be possible and, therefore, we propose to adopt this approach as future standard. For this reason, we also developed a computer program to perform the fit of the model to measured data.

12 páginas, 10 figuras, Octahedrally-coordinated Cr3+ possesses peculiar spectral features which made easy to identify it in minerals, even in minor amounts. Chromium has been studied in uvarovite and fuchsite by optical and EPR spectra. Optical, EPR, FT-infrared and EPMA studies have also let to determine the presence of Fe3+ and Ti3+ and fluid inclusions within uvarovite and fuchsite. Absorption and scattering effects on the optical spectra obtained for Cr-bearing samples, resulting from the presence of inclusions, are also discussed in this work., This work was financed by Research Project BT2000-0582 (S.E.U.I.D.-M.C.T., Spain)

15 páginas, 8 figuras, Chemical and textural studies show fibrous rosasite crystals, with a spread Cu : Zn ratio, occuring in a calcite matrix together with goethite, psilomelane, quartz and saponite in oxidation zones of copper ore deposits. Aurichalcite occurs also as fibrous crystals and has a more fixed composition (Cu : Zn ratio is 1.3 : 3.7). Aurichalcite sample also contains prismatic hemimorphite. The nature of the copper ion and its site symmetry in rosasite and aurichalcite were investigated using a combination of optical absorption and EPR spectroscopy. Optical absorptions of rosasite exhibited three bands due to Cu2+ in tetragonally elongated octahedral site and the parameters evaluated from the observed band positions are Dq = 1480, Ds = 2330 and Dt = 410cm-1. The EPR features observed in rosasite (g > g||) is an indication of predominant interactions within the copper ions (Cu Zn). Optical and EPR spectra of aurichalcite sample account for Cu2+ ion in the distorted octahedron site. The molecular structures of the two copper zinc carbonate hydroxide minerals were also studied by FTIR spectroscopy. The infrared spectra of the two minerals are different in line with differences in crystal structure and composition. The shift towards lower wave numbers of the carbonate bands and splitting of bands are more in aurichalcite than the other. This indicates that the symmetry of CO32- ion in both the minerals is lowered from D3h to C2v or Cs and distortion is more in aurichalcite., This work was financed by Research Project BT2000-0582 (S.E.U.I:D.-M.C.T., Spain)

The effects of a subvolcanic intrusion on its host rocks in the Priego de Córdoba area (SE Spain) was studied by optical microscopy, X-ray diffraction and electron microscopy. The intrusion of a laccolith of stratiform dolerite in partially consolidated marly sediments at quite shallow depths below the ocean floor took place during the intracontinental rifting phase of the Subbetic zone of the Betic Cordilleras. In the first stage, contact metamorphism caused the crystallization of calc-silicate consisting of grossular andradite garnet, diopside, vesuvianite and titanite for which the upper temperature limit was 500°C. Phyllosilicates are found in a network of veins cross-cutting the carbonate and calc-silicate matrix, indicating their formation during a process of hydrothermal alteration superimposed on the contact aureole. In the area closest to the subvolcanic rocks, saponite is the main phyllosilicate although some dispersed chlorite is found. In the zone furthest from the contact, corrensite together with saponite and beidellitic smectites were observed. The presence of low-temperature phases (saponite) in the area closest to the laccolith reveals the evolution of the hydrothermal system toward cooler conditions. In the early stage, the circulation of a hot hydrothermal fluid caused the crystallization of chlorite in the area surrounding the subvolcanic body and corrensite in the more distal area, which might have begun even during the contact metamorphism stage. A cooling phase followed, resulting in the crystallization of saponite in the host rocks, and the crystallization of dioctahedral and trioctahedral smectites inside the subvolcanic body.

15 páginas, 8 figuras, 4 tablas, Chlorites from Cambrian basaltic vesicular lavas, characterized by relatively high Xc (0.81–0.98), gave temperatures of formation of 285 to 350°C (Cathelineau’s empirical geothermometer). Both the Xc and temperature calculations gave results which were too high for the diagenetic conditions indicated by the interbedded shale mineralogy. The HRTEM and XRD studies indicate the absence of smectite layers in these chlorites; i.e. according to lattice images, the actual value of Xc is 1. The chlorite composition in these basaltic lavas must, therefore, be explained in relation to their whole-rock geochemistry, with which a good correlation has been found. The basaltic lavas are characterized by relatively high FeO/MgO ratios (3.2831.66) and must be considered as an Fe-rich system, with similar chemical behaviour to pelitic rocks. In these cases, direct chlorite formation, without a previous smectite precursor, is a normal occurrence and the Xc calculation and empirical geothermometric calculations are inadequate., Proyecto de investigación BTE2000-0582 del Ministerio de Ciencia y Tecnología, y el Grupo de Investigación RNM-0179 de la Junta de Andalucía.

The main focus of this paper is to model the daily series of banknotes in circulation in the context of the liquidity management of the Eurosystem. The series of banknotes in circulation displays very marked seasonal patterns. To the best of our knowledge the empirical performance of two competing approaches to model seasonality in daily time series, namely the ARIMA-based approach and the Structural Time Series approach, has never been put to the test. The application presented in this paper provides valid intuition on the merits of each approach. The forecasting performance of the models is also assessed in the context of their impact on the liquidity management of the Eurosystem. JEL Classification: C22, C51, C53, C59

15 páginas, 12 figuras, 4 tablas, The alteration process of a subvolcanic rock with calcic plagioclase, pyroxene, and olivine as major components was investigated by X-ray diffraction (XRD) and analytical and transmission electron microscopy (TEM/AEM). Experimental interaction with 1 M NaOH solution led to the formation of dioctahedral beidellite to Fe-rich montmorillonite after 1 and 3 d of reaction. This range of smectite composition is similar to that from natural subvolcanic-derived soil formed from the same parent material. After 14 d of reaction, a berthierine-smectite (B-S) interstratified clay had partially replaced the smectite. Although, the presence of smectite interlayers prevented analysis of pure berthierine, berthierine-rich B-S interstratifications have a composition similar to pure berthierine. After 40 d, the alteration process led to a 7-Å S interstratifications whose composition falls between greenalite and lizardite. A series of amorphous materials were also found in the 14 and 40-d experiments. The most abundant of these is a Si-Ca-Fe-rich material, whose chemical composition approaches that of the starting rock. In contrast, two other amorphous materials had a smectitic composition., Proyecto de investigación BTE2000-0582 del Ministerio de Educación e Investigación y el Grupo de Investigación RNM-0179 de la Junta de Andalucía.

19 páginas, 10 figuras, 5 tablas., [EN] Devonian and Carboniferous metasedimentary sequences in the southernmost sector of the Iberian Massif, part of the Hercynian Orogen in southwestern Portugal, contain shales and slates of low but variable metamorphic grade. These rocks have been studied by optical microscopy and XRD to obtain basic data on their clay mineralogy and crystal-chemical parameters (IC, the index of "crystallinity", b and d001). Electron-microscopy techniques (SEM, HRTEM and AEM) have been used to characterize the textural relationships and chemical evolution of the minerals, mainly the phyllosilicates. A good correlation has been found between the data determined by XRD methods and by electron microscopy. The main mineral association is quartz + dioctahedral K-rich mica + feldspars, but Na–K intermediate mica, paragonite, kaolinite and chlorite also are present, although discontinuously. The thickness of crystallites measured directly from lattice-fringe images is related to the IC, providing information on the evolution of the metamorphism through the sequences, with decreasing IC from southwest to northeast. The IC values for both the Brejeira and Mira formations correspond to diagenesis and anchizone, the Mértola and Phyllite–Quartzite formations, to high anchizone–epizone, and the Pulo do Lobo Formation presents values typical of epizonal conditions. Despite this pattern of evolution, however, the changes in metamorphic grade are not progressive, and the abrupt changes found between the characteristic values of each stratigraphic formation are interpreted as being associated with thrust surfaces. Textural data provide a clear contrast between the samples of different grade, with the lowest-grade samples showing a bedding-parallel microfabric and stacks of phyllosilicates. The most strongly metamorphosed pelites, on the other hand, present a crenulation-cleavage microfabric and a recrystallized matrix. As grade of metamorphism increases, crystal thickness increases and defects decrease in the phyllosilicates, although chlorite shows a higher density of strain-related defects than mica. There is wide scatter in the chemical data for both dioctahedral micas and chlorites, but some chemical characteristics can still be discerned. XRD and AEM reveal a tendency for the micas to be more similar to muscovite and less to illite with increasing metamorphic grade, although both compositions are present in all samples. The extent of phengitic substitution is extremely low, indicating low-pressure conditions. The formation of chlorite and its composition are mainly controlled by the host-rock composition., [FR] Les séquences métasédimentaires dévoniennes et carbonifères du secteur extrême-sud du Massif Ibérique, faisant partie de l’orogène hercynienne dans le sud-ouest du Portugal, contient des shales et des ardoises formés à un degré de métamorphisme faible mais variable. Ces roches ont été étudiées par microscopie optique et par diffraction X afin d’obtenir des données de base à propos de leur contenu en argiles et les paramètres cristallochimiques associés (IC, l’indice de “cristallinité”, b et d001). Les techniques de microscopie électronique à balayage, microscopie électronique à haute résolution et microscopie électronique analytique ont été utilisées pour caratériser les relations texturales et l’évolution chimique des minéraux, surtout les phyllosilicates. Une bonne relation existe entre les données obtenues en diffraction X et celles obtenues par microscopie électronique. L’association principale de minéraux est quartz + mica dioctaédrique riche en K + feldspaths, mais les roches contiennent aussi un mica intermédiaire à Na–K, paragonite, kaolinite et chlorite, quoique de façon non uniforme. L’épaisseur des cristallites, mesurée directement à partir des images de franges réticulaires, est liée à l’indice de cristallinité, et fournit donc une information à propos de l’évolution du métamorphisme dans ces séquences: l’indice de cristallinité diminue du sud-ouest vers le nord-est. Les valeurs de cet indice dans les roches des formations de Brejeira et Mira correspondent à celles attendues d’un milieu de diagenèse ou de l’anchizone; dans les roches des formations Mértola et Phyllite–Quartzite, elles correspondent à l’anchizone supérieur ou à l’épizone, tandis que dans la Formation de Pulo do Lobo, elles sont typiques de l’épizone. Malgré cette disposition en zones, les changements en degré de métamorphisme ne seraient pas progressifs. Les démarcations abruptes entre les valeurs caractéristiques de chaque formation stratigraphique résulteraient de la présence de surfaces de chevauchement. Les données texturales fournissent une indication claire du degré de recristallisation, les échantillons les plus faiblement recristallisés produisant une microstructure parallèle au litage et des empilements de phyllosilicates. En revanche, les échantillons pélitiques les plus intensément recristallisés contiennent un clivage dû à un microplissement, et une matrice recristallisée. A mesure qu’augmente le degré de métamorphisme, l`épaisseur des cristaux augmente, et la densité de défauts diminue dans les phyllosilicates, quoique la chlorite possède une densité plus élevée de défauts dus à la déformation que le mica. La composition des micas dioctaédriques et de la chlorite varie grandement, mais il est encore possible d’en extraire certaines généralités. Les données obtenues par diffraction X et par microscopie électronique analytique montrent une tendance pour le mica dioctaédrique de ressembler davantage à la muscovite qu’à l’illite à mesure que l’intensité du métamorphisme augmente, quoique les deux compositions sont présentes dans tous les échantillons. La portée d’une substitution vers la phengite est très limitée, conforme à la faible pression de recristallisation. La formation de la chlorite et sa composition dépendent surtout de la composition de la roche-hôte., The TEM study has been supported by NSF grant EAR–9418108. Financial support was also supplied by Research Project nº BT2000–0582 and FPI research grant to I.A., both from the Spanish Ministry of Science and Technology and Research Group RNM–0179 of the Junta de Andalucía.

11 páginas, 9 figuras, 2 tablas, Muscovite-kaolinite intergrowths found in Albian sandstones of the Basque Cantabrian basin (northern Spain) were studied by optical, scanning and electron microscopy and electron microprobe analysis. Kaolinitization begins at grain edges, forming the characteristic fanned-out textures, and propagates toward the interior along the cleavages of muscovite. Kaolinite and muscovite occur as thick packets, being free of interlayering. Phase boundaries between both minerals show bidimensional crystallographic continuity, and no intermediate phases have been identified. The data obtained suggest that muscovite only supplied a template suitable for the epitactic crystallization of kaolinite, while Al was available in sufficient amounts due to the dissolution of detrital K-feldspar. Very small packets of magnetite or maghemite showing a coherent orientation with the kaolinite crystals have been recognized, and could be responsible for the small Fe contents usually detected in electron microprobe analyses of kaolinite. Textural relationships between authigenic kaolinite and deformation microstructures in the intergrowths, combined with previous information about burial conditions, show that alteration proceeded during a late stage of the diagenetic history, related to the uplift of the studied materials as a result of the Alpine orogeny., Este trabajo se ha financiado con los proyectos PB95-0343-A y BTE2000-0582 (DGI, Ministerio de Ciencia y Tecnología) y Grupo de Investigación RNM-0179 de la Junta de Andalucía.

14 páginas, 5 figuras, 4 tablas, Analytical electron microscopy of representative smectites from soils and sediments revealed that K was present in significant proportions. It was the major interlayer cation in soils from pelitic rocks, continental and marine sediments, independent of their diagenetic grade. Sodium was predominant only in soils from basic rock. Fluvial sediments contained smectites with both kinds of interlayer compositions. The octahedral composition of each sample ranged widely, covering various fields of dioctahedral smectites. The most important trend was the substitution of Al by Fe and Mg; the chemistry of each smectite particle was determined by the parent mineral from which it formed. The real interlayer composition has important implications for the diagenetic smectite-illite transformation. When considering a typical K content, the smectite-illite reaction, with chlorite and quartz as subproducts, needs only 0.21 K atoms. For more K-rich compositions, a reaction is possible without an external supply of K., Proyecto de investigación PB96-1383 del Ministerio de Educación e Investigación y el Grupo de Investigación RNM-0179 de la Junta de Andalucía.

11 páginas, 9 figuras, 2 tablas, This study examines the evolution of the texture, structure, and chemical composition of rocks derived from elastic materials of the Ossa-Morena Zone (Hesperian Massif, Spain). Previous studies of phyllosilicates in these rocks (by X-ray diffraction, scanning electron microscopy with energy- dispersive X-ray analysis, and electron microprobe) indicated a temperature decrease from bottom (epizone conditions) to top (diagenetic conditions) of the rock section. At the nanometer scale, phyllosilicate packets form large angles where grains intersect with no preferred orientation. With metamorphic grade, packets are wide and defect free, compared to packets at lower grade. These packets are similar to 15 Layers under diagenetic conditions to >80 layers in the epizone. Dioctahedral K-rich micas (muscovite, phengite, and illite) have coexisting 1M(d), 1M, and 2M polytypes. Long-period polytypes of 4, 5, and 6 layers are reported for the first time in dioctahedral K-rich micas. The chemical compositions of the micas are nearly identical in the anchizone and the diagenetic zone, comprising an illitic (0.8 atoms per formula unit, a.f.u., of K) and a phengitic component (0.15 a.f.u. of Mg and 0.13 a.f.u. of Fe). Fe may correspond to a ferrimuscovitic substitution. Epizone samples have a high phengitic content (Mg = 0.24 a.f.u.) and almost no illite component. One diagenetic sample has coexisting berthierine, trioctahedral chlorite, sudoite, and corrensite. Berthierine and chlorite are identical in composition. Because of the elastic nature of the system, the composition of corrensite is not typical of other corrensites, with higher Al content, Fe/Mg ratio at similar to 1, and K as the exchangeable cation. Textural differences between the diagenetic zone and the anchizone are the progressive increase in the size of dioctahedral K-rich mica grains, which involves an increasing illite crystallinity based on the Kubler index. The chemical compositions of these micas are illite (diagenesis and anchizone) and phengite in the epizone. There are no intermediate phases, suggesting a compositional gap between illite and phengite. The coexistence of different polytypes of dioctahedral K-rich micas and the absence of chemical homogeneity indicate disequilibrium in the Cambrian pelitic rocks studied, Proyecto de investigación PB96-1383 del Ministerio de Educación e Investigación y el Grupo de Investigación RNM-0179 de la Junta de Andalucía.

25 páginas, 11 figuras, 2 tablas, Detailed research in the eastern part of the Alpujarras region, Betic Cordilleras, has revealed the existence of large recumbent fold structures involving lithological sequences previously considered to belong to different tectonic units. We have reconstructed a large, complex fold structure (which can be followed axially for over 50 km) based on a careful revision of the boundaries between lithological formations, a structural analysis of the carbonate and metapelite sequences, and the use of mineralogical techniques such as measurements of d001 basal spacing of phengite, paragonite and chlorite, determinations of the illite ‘crystallinity' index (IC) and b0 parameters of mica and chlorite. Structural field data described in this paper include gently dipping axial plane cleavage surfaces, common occurrence of gently dipping boudinage and pinch-and-swell structures and associated sub-orthogonal stretching lineation, similarity in orientation of this stretching lineation with the slip direction of the low-angle normal faults, and close association between north-facing recumbent folds and top-to-the-north low-angle normal faults (the slip direction of the faults being broadly perpendicular to the fold axes). These features clearly indicate that extensional processes played a decisive role in the generation of the Alpujarras large recumbent folds. The development of these recumbent folds probably occurred during the Early to Middle Miocene extensional tectonics that affected the Betic Cordilleras. The formation of large-scale folds in association with normal faulting is consistent with the P–T paths and geochronological data established for the Alpujarride region., This study was supported by grants PB95-1219 and PB92-0020-CO2-01.

14 páginas, 3 figuras, 4 tablas, The crystallographic parameters, intensity relationships of basal reflections, and optical properties of chlorites from the low-grade metamorphic metapelitas of the Alpujárride Complex (Betic Cordillera, SE Spain) have been compared with EMPA data obtained from areas selected from backscattered electron images. The Rausell-Colom et al. (1991) formula gives the best results for the calculation of A1IV from d001, corrected according to the Fe content, which may be obtained from the new equation b0 = 9,2216 + 0,0293 (Fe+Mn). This relationship gives intermediate results between those obtained by the Brindley (1961) and Von Engelhardt (1942) equations. Poor results are obtained by intensity relationship of basal reflection methods, due to uncertainty in the conversion of intensities to structure factors. Sign of elongation and anomalous interference colours depend exclusively on the Fe/(Fe+Mg) ratio and are independent of the A1IV content. The joint use of these two optical properties allows the classification of chlorite and the recognition of coarse compositional differences between various chlorites of the same thin section. The proposed methods also allow two of the three mean compositional vectors of chlorite defined by Laird (1988) to be determined. Dioctahedral substitution has been found to be low and fairly constant but significant, with an average value of Σoct = 5,9 a.f.u. and a standard deviation of 0,03.

12 páginas, 11 figuras, 3 tablas, Interleaved phyllosilicate grains (IPG) of various compositions are widespread in low-grade Verrucano metasediments of the northern Apennines (Italy). They are ellipsoidal or barrel shaped, up to 300–400 μm long and they are often kinked and folded; phyllosilicate packets occur as continuous lamellae or as wedge-shaped layers terminating inside the grain. Using electron microscopy techniques (SEM, TEM) six types of IPG have been distinguished on the basis of their mineralogical composition: (1) Chl+Ms ± Kln; (2) Chl+ Ms+Pg ± Kln; (3) Ms+Prl ± Pg; (4) Ms+Prl+Su; (5) Ms+Prl+Chl+Su; (6) Su+Ms. Types (1) and (2) are mainly composed of chlorite, with Ms and Pg as minor phases; Kln grows on Ms in highly weathered samples. Types (3), (4), (5), and (6) are composed of muscovite, with intergrown Prl, Chl, Su and new-formed muscovite. The IPG show all kinds of contacts: from coherent grain boundaries with parallel basal planes and along-layer transitions to low- and high-angle grain boundaries. The IPG formed on pristine minerals such as chlorite and muscovite. The transformations took place during the prograde and retrograde metamorphic path of the rocks: they were facilitated by deformation and they occurred in equilibrium with a fluid phase, which allowed cation diffusion. Prograde reactions [Chl = Ms (or Pg); Ms = Prl; Ms = Chl] involve dehydration and sometimes a decrease in volume, whereas retrograde reactions (Ms = Kln; Ms = Su) involve hydration and an increase in volume. These transformations do not simply occur through an interchange of cations, but often involve deep structural changes: transitions from one phyllosilicate to another generally proceed through dissolution-recrystallization reactions. In conclusion, Verrucano IPG represent microstructural sites which have not completely equilibrated with the whole rock and whose mineral assemblage depends on the original composition of the microstructural sites., Financial support was supplied by the Italian Ministry of University and Scientific and Technological Research grants (MURST to I.M.) and Research Projects nº PB92-0961 and PB92-0960 of the Spain Ministry of Education as well as Research Group 4065 of the Junta de Andalucia

6 páginas, 2 figuras, 2 tablas, New data on the evolution of the Mn-Mg chlorite compositional gap toward Fe-rich compositions have been obtained from a nodule of metamorphic rock included in the Sierra Albarrana pegmatite body. Mn-rich chamosites were formed as a result of the decomposition of spessartine-rich almandine. The gap defined by Schreyer et al. (1986) for Mg-rich compositions persists in the Fe-rich region of the Mn-Mg-Fe compositional triangle and closes near the Fe-Mn side.

10 páginas, 8 figuras, 7 tablas, Dioctahedral smectite is present as a retrograde alteration product of chlorite in Permian-Triassic red slates of the Malaguide Complex in Sierra de Espuña (Betic Cordillera). Mineral assemblages and textures, illite crystallinity indices, and fluid inclusion data indicate sub-greenschist facies conditions that reached at least 180°C in the higher-grade tectonic unit of the Malaguide Complex, preceding formation of smectite. Smectite, having K as the dominant interlayer cation, occurs ubiquitously intercalated with trioctahedral chlorite as thin packets of layers and as individual layers that commonly change to chlorite along layers. Although some chlorite is typically homogeneous and trioctahedral, much chlorite shows signs of alteration and has compositions corresponding to different degrees of smectite contaimination. The incompatibility of metamorphic grade with the occurrence of smectite, the general association of chlorite and smectite, and the textural relations collectively show that dioctahedral smectite is derived through replacement of trioctahedral chlorite. Such replacement occurs on a regional basis and demonstrates that caution must be used in interpreting the occurrence of smectite in pelites as being due to prograde processes. Alteration of trioctahedral chlorite under oxidizing conditions due to introduction of phreatic water after uplift of the Betic Cordillera is proposed as the cause of formation of smectite., Proyecto de investigación PB92-0961 y BE90-234 a F. Nieto (DIGICYT, España), Grupo de Investigación 4065 de la Junta de Andalucía y NSF 88017080 y 91-04565 a Donald R. Peacor.

The lower Cretaceous of the Bilbao Anticline is built up of a thick sequence of sediments. Three main sedimentary systems are been defined traditionally: Wealdian, Urgonian, and Supraurgonian ones. Pelitic facies were collected from four crossing sections to the structure. XRD was used to analyse the distribution of clay minerals, Kubler index (KI) and some illite crystallochemical parameters. Clay minerals are strongly source controlled. Illite/smectite interstratified distribution and KI, indicated a diagenetic grade which is increasing with deep of buria!' Middle and deep diagenetic grades are been identified and anchimetamophism in the most deeply buried samples of the central area, with no schistosity. Bearing in mind the maximum burial depth and vitrinite reflectance values, unusual presence of a R1 illite/smectite interstratified mineral has been detected in some samples.

13 páginas, In order to obtain an indication of metamorphic conditions we have studied the mineralogy of the clastic rocks, in particular the phyllosilicates, from three Precambrian series in the Central-Iberian and Ossa-Morena zones of the Southern Hesperian Massif: the Esquisto Grauváquico Complex; the so-called Serie Negra; and the Azuaga Formation. For this purpose we have used the crystal-chemical parameters obtained via X-ray diffraction (d001, b0, ratios of the basal intensity of the white micas and chlorites, and the crystallinity index of the mica) together with electron microprobe data from selected areas, obtained via backscattered electron images. The mineral assemblages, commonly quartz+muscovite +albite +chlorite ±biotite, and the values obtained for the illite crystallinity index (between 0.18° and 0.20° 2Θ) in rocks with non-diagnostic mineral assemblages point to at least greenschist-facies metamorphic conditons. The phengite content of the mica indicates an overall pressure regime near the limits between low and intermediate pressure, but some significant differences exist between the series studied. The Azuaga Formation shows the lowest pressure (about 4 kbar), while the Serie Negra indicates a pressure of at least 1 kbar more. In the Esquisto Grauváquico Complex, when the samples are considered overall, the results are similar to those of the Serie Negra, but there is inhomogeneity in the rocks from the two sections studied. The various types of chlorite, both textural and optical, are homogeneous in composition in each rock specimen and their chemical composition depends primarily on the composition of the host-rock.

The paleozoic stratigraphic sequence outcropping on the southern border of the Sierra de la Demanda, whose age ranges from the Cambrian to the Ordovician, has been divided into six different formations. According to their facies, these are equivalent to the those outcropping in the westernmost sector of the West Asturian-Leonese Zone (WALZ). The rocks have been affected by two hercynian deformation phases and a late hercynian fracturation. The first hercynian phase originated folds and all knids associated with a primary foliation; the second phase gave rise to overridings and occasionally a crenulation cleavage. The deformation is accompanied by low and very low-grade regional metamorphism with intensity decreasing in the general terms towards the SE. Cristallochemical data of the samples obtained by means of X-ray powder diffractometry, have revealed the epizone-anchizone limit and, in sorne cases, have evidenced the metamorphic jump produced by the faults.

In order to find a reliable index of fetal wellbeing, maternal estriol, hCS and oxytocinase levels were related with condition of the neonate. Fifty six high risk pregnancies were studied. Estriol and hCS were determined by specific radioimmunoassay and oxytocinase with a colorimetric method. The condition of the newborn was evaluated by the APGAR score. Neonates were divided into two groups, depressed (APGAR score 0-6) and vigorous (APGAR score 7-10). When the mean birthweights of both groups were statistically different, maternal estriol levels were corrected to avoid the influencing factor of newborn weight. Mean maternal estriol level corresponding to vigorous newborns was 46.73 ng/ml. This value was statistically higher than that corresponding to the group of depressed newborns, which was 26.25 ng/ml (Fig. 1). The mean birthweight of depressed infants (2,382.75 g) was statistically lower than that of the vigorous group (3,044.75 g). The corrected mean maternal estriol values of vigorous neonates (45.44 ng/ml) was different from that of depressed ones (25.14 ng/ml) (Fig. 2). When patients were divided according to maternal diseases (diabetes, vascular pathology, Rh sensitization) serum estriol levels of the mother were statistically different according to the Apgar score of the newborns. There was no significant difference between serum hCS and oxytocinase levels of mothers with depressed and vigorous newborns. Discarding fetal weight as an influencing factor in maternal hormone level, our results indicate the suitability of maternal serum estriol determinations to predict condition of the newborns in high risk pregnancies.

Postnatal growth patterns of weight, length/height and head circumference in full-term (FTI), preterm (PTI) and small-for-dates (SFDI) infants, are described by using distance and velocity data together with the concept of growth per unit of body weight. The study was performed in 112 healthy Caucasian infants, of a similar socioeconomic status, in Montevideo, Uruguay. Median growth velocity (MGV) and median growth velocity per unit (MGVU) of body size are defined. The authors stress that: (a) growth velocity is related to body mass, (b) a useful evaluation of growth is made by using two consecutive measures with a certain time interval independently of birthweight and gestational age, and (c) expressing growth per day per unit relates well to daily nutritional and other requirements.

4 páginas, 4 figuras, 3 tablas., The crystal structure of the complex catena-bis(u-6-amino-3-methyl-5-nitrosouraci1ato-N5 ,O4, N1, O2)cadmium(II) has been determined. It crystallizes in the tetragonal space group P41212-D44 with cell dimensions a = b = 7.885 (0) A, c = 26.359 (2) A, V = 1638.8 (1) A3, and Z = 4. The structure was solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R = 0.018 for 1956 data. The structure consists of a sequence of complex polyrneric sheets, linked by hydrogen bonds. Each ligand is coordinated to two different cadmium atoms, and each cadmium atom is coordinated by four pyrimidine ligands. These ligands are equivalent with one cadmium atom binding through N5 and 04 atoms, while the other cadmium atom binds through the N1 and 02 sites. The cadmium atom is eight-coordinated and shows a C2 symmetry that can be described as a dodecahedron with the mmmm arrangement of ligands. The A vertices are al1 occupied by oxygen atoms and the B vertices by nitrogen atoms.

Head circumference and its cross-sectional area, biparietal and fronto-occipital diameters, abdominal circumference and its cross-sectional area, and the transverse and anteroposterior diameters were measured in 30 healthy single fetuses from normal pregnancies by means of ultrasound. The 5th, 50th and 95th percentiles of distance and velocity curves are described. The comparison of the values of a perimeter (abdominal or cephalic) measured directly from the photograph or calculated by the ellipse formula, showed a straight correlation. The use of the ellipse formula in current practice may simplify and reduce the cost of this technology.

The purpose of this study was to determine whether the early artificial rupture of the amniotic membranes performed to shorten the duration of an otherwise normal labor and delivery might have potentially deleterious effects on the fetus that would be reflected in the neonate. In 38 infants delivered at term, acid-base balances and O2 and CO2 pressures were obtained in umbilical arterial and venous blood at birth, prior to the first inspiration. For the purpose of the study the infants were divided into two groups: group I infants were born after a normal labor in which the amniotic membranes were permitted to rupture spontaneously at full cervical dilatation; group II infants were born after a labor in which the membranes were ruptured artificially when cervical dilatation was 4 to 5 cm. There was no evidence of fetal distress, and all infants were vigorous at birth. The pH of umbilical venous blood was greater in the group with late rupture of the membranes (fiftieth percentile [P50] = 7.36) than in those born after early amniotomy (P50 = 7.30) (p less than 0.01). The pH values of umbilical arterial blood were also higher in the group I infants (P50 = 7.31) than in those born after amniotomy (P50 = 7.25)(p less than 0.025). These differences were also observed in the 19 neonates in whom the cord was not encircled around the neck at the time of birth. The PCO2 in umbilical venous blood was less, and the hemoglobin saturation was greater (P less than 0.05) in group I infants than in those of group II. It is possible that the influence of early amniotomy on fetal pH may be deleterious in infants born after high-risk pregnancies in which the uteroplacental circulation is impaired.

A pneumotachographic method for assessment of pulmonary dynamics in critically ill newborns in an intensive care setting was developed in our laboratory. Before the results obtained with this method could be applied, the normal range of values were determined in 48 normal term and preterm newborns. Their body weight ranged between 1200 and 4100 g, and postnatal ages between 24 hours and 21 days. In three infants, two determinations were performed after an interval of 7 days. The studies were performed with a pneumotachograph applied to the upper airway by means of an inflatable face mask or latex nasal prongs. The air flow signal was electronically integrated to time to produce a volume signal. Airway pressure was determined proximal to the pneumotachograph. Esophageal pressure was determined with a water filled catheter placed in the lower third of the esophague. Tidal volume (VT), minute ventilation (V), Dynamic compliance (Cdyn), total pulmonary resistance (R), total pulmonary work (Wt), Elastic work (We), and flow resistive work (Wv), were determined. A significant linear correlation was found between Cdyn and body weight (r = 0.50, p less than 0.01) whereas no significative correlation was found between body weight and VT, V or R. Values for VT, V and Cdyn were corrected for body weight and means (X), standard deviation (SD) so as 10th and 90th percentiles are shown in table III. X, SD and percentiles for R were shown in table III. Wt, We and Wv were corrected for V, and X, SD and percentiles shown in table III. Values of VT/Kg, Cdyn/Kg and R are similar to those found by other authors with pneumotachography and plethysmography. The V/Kg values obtained by us were higher than those reported by other authors, which together with the lack of correlation of VT and V with body weight, question the reliability of V values in our study. This could be explained by: 1) excessive increase in dead space in cases in which a face mask was used; 2) nocioceptive stimulus produced by face mask or nasal prongs; 3) inadequate selection of the moment at which the record was obtained. Whichever the explanation, our values of V cannot be considered as basal, and should be interpreted with caution. The results obtained allow us to continue with our program and apply this method to the study of newborn infants with RDS.

The crystal structure of the complex catena-bis(~-6-amino-3-methyl-5-nitrosouraciIato-~,~,N',~)cadmium(II) has been determined. It crystallizes in the tetragonal space group P41212-0: with cell dimensions a = b = 7.885 (0) A, c = 26.359 (2) A, V = 1638.8 ( I ) A', and Z = 4. The structure was solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R = 0.018 for 1956 data. The structure consists of a sequence of complex polymeric sheets, linked by hydrogen bonds. Each ligand is coordinated to two different cadmium atoms, and each cadmium atom is coordinated by four pyrimidine ligands. These ligands are equivalent with one cadmium atom binding through N5 and 0 4 atoms, while the other cadmium atom binds through the N1 and 0 2 sites. The cadmium atom is eight-coordinated and shows a C, symmetry that can be described as a dodecahedron with the mmmm arrangement of ligands. The A vertices are all occupied by oxygen atoms and the B vertices by nitrogen atoms.

Han sido múltiples las soluciones aportadas, y el problema esta lejos aún de haber entrado en vía de liquidación. Algunos autores las suponen compuestas antes del destierro en Corcega, es decir, antes del año 41, al menos en parte. Otros, durante el destierro (a. 41-49). Otros, desde el regreso del destierro hasta su retiro a la vida privada (a. 49-62). Finalmente, otro grupo de críticos opinan que han sido compuestas después de su retiro (a. 62-65), o bien, a lo largo de toda su vida de escritor.

El estásimo primero de la tragedia sofóclea Antígona, es, sin duda alguna, el más importante de la presente tragedia y también uno de los más bellos de toda la lírica coral de los poetas trágicos de la Hélade.

Una de las notas características de la filosofía de Séneca es su orientación a la praxis. Más que una ordenación sistemática de principios, es una sabiduría práctica de la vida. Los problemas teóricos ocupan en la filosofía de Séneca un lugar secundario, y el pensamiento, según él, debe estar al servicio de la moral, de tal modo, que todo lo que no sirve para la ordenación moral de la vida humana carece de valor. Pero las pcrincipales acusaciones de Séneca van dirigidas no contra toda especulación, sino contra el abuso de la misma, contra las puras especulaciones de escuela que sólo sirven para retardar o impedir la conquista del bien. En general, admite los principios fundamentales de la escuela estoica y no duda en recurrir a otros grandes maestros, como Platón, Pitagoras y el mismo Epicuro, cuando lo juzga necesario para justificar sus posturas ante los problemas que la moralización del hombre plantea.