Taphonomic analysis of fossil concentrations from La Manga Formation (Oxfordian), Neuquén Basin, Mendoza Province, Argentina

Griphaeid-dominated fossil concentrations of La Manga Formation are characterized on the basis of taphonomic, sedimentologic, stratigraphic and palaeoecologic criteria. These concentrations are present in the basal deposits (Unit 1) of three outcrops in the locality of Bardas Blancas. Their attributes allow distinguishing seven different fossil accumulations: A) Channelized fossil concentrations of Gryphaea sp.; B) Shell beds of Gryphaea sp. highly reworked; C) Shell beds of Gryphaea sp. moderately reworked; D) Accumulations of Gryphaea sp. with biomicrite to biopelmicrite matrix; E) Shell detritus; F) Accumulations produced by bottom currents; and G) Accumulations found in clumps. Accumulations A-C were deposited by high energy processes (storm waves and currents) in the upper middle ramp. Accumulations D and E were produced by high energy processes (storm waves and currents) but the final depositions were produced out of suspension in low energy environments, in lower middle ramp settings. Accumulations F were generated by weak bottom currents, meanwhile accumulations G correspond to gryphaeids associations reworked by bioturbators or by hydraulic processes after variable periods of permanence in sediment/water interface. Both are interpreted as lower middle or outer ramp. This interpretation suggests that these deposits that in previous works were interpreted as outer ramp settings, characterize middle and outer ramp settings. The vertical distribution of fossil concentrations from upper middle ramp to lower middle and outer ramp settings evidences a continuously growing accommodation space and allows to interpret the Unit 1 as part of a transgressive systems tract.Las concentraciones bioclásticas dominadas por grifeidos de la Formación La Manga (Oxfordiense) de la Cuenca Neuquina fueron caracterizadas sobre la base de criterios tafonómicos, sedimentológicos, estratigráficos y paleoecológicos. Estas concentraciones están presentes en los depósitos basales (Unidad 1) de tres afloramientos en la localidad de Bardas Blancas. Sus atributos permitieron distinguir siete tipos diferentes de concentraciones bioclásticas: A) concentraciones bioclásticas canalizadas de Gryphaea sp.; B) Estratos de conchillas de Gryphaea sp. fuertemente retrabajadas; C) Estratos de conchillas de Gryphaea sp. moderadamente retrabajadas; D) Acumulaciones de Gryphaea sp. con matriz biomicrítica y biopelmicrítica; E) Detrito de conchillas; F) Concentraciones generadas por corrientes de fondo; y G) Agrupaciones de conchillas (clumps). Las acumulaciones A-C fueron depositadas por procesos de alta energía (olas y corrientes de tormenta) en sectores de rampa media superior. Las acumulaciones D y E fueron generadas por procesos de alta energía (olas y corrientes de tormenta) pero la depositación final ocurrió por decantación en ambientes de baja energía, en la rampa media inferior. Las acumulaciones F fueron generadas por débiles corrientes de fondo, mientras que las acumulaciones G corresponden a asociaciones de grifeidos retrabajadas por organismos bioturbadores o por procesos hidráulicos después de períodos variables de permanencia en la interfase agua/sedimento. Ambas acumulaciones fueron interpretadas como depósitos de rampa media inferior o rampa externa. La distribución vertical de concentraciones bioclásticas desde ambientes de rampa media superior hasta ambientes de rampa media inferior y rampa externa, evidencia un aumento en el espacio de acomodación y permite interpretar a la Unidad 1 como parte de un cortejo transgresivo

Oxfordian microbial laminites from La Manga Formation, Neuquén Basin, Argentina: Remarkable nanobacteria preservation

Exceptionally preserved stromatolites have been found in the shallow marine carbonate facies of the Callovian-Oxfordian La Manga Formation, in the Neuquén Basin (Argentina). The stromatolites exhibit planar and crinkle lamination, often disrupted by sheet-cracks, mudcracks, and fenestral structures, which indicate periodic subaerial exposure. These and other evidences suggest that these stromatolites grew in low energy upper intertidal to lower supratidal environments. They consist of fine micrite/microsparite crystal fabrics (with a remarkable lack of allochems) that define submillimiter alternations of dense laminae. Extensive SEM examinations of polished samples of the stromatolites reveal exceptional preservation of rod-shaped bacteria, coccoid like microorganisms, and abundant aggregates of framboidal pyrite. The rod-like bacteria consists of a network of irregular distributed filaments, which range from 150 nm to an uncommon 640 nm in length; diameters range from 54 nm to 90 nm. Subspherical bodies range in size between 70 and 89 nm. The presence of abundant framboidal pyrites is interpreted as the result of the metabolic activity of sulfate–reducing bacteria and decay of organic matter.Se describen estromatolitos excepcionalmente preservados en facies carbonáticas marinas someras en la Formación La Manga, de edad Calloviense-Oxfordiense, en la Cuenca de Neuquén (Argentina). Los estromatolitos muestran una laminación tanto planar como ondulada, frecuentemente alterada por estructuras de tipo fenestral, y sheet y mud-crack, que indican etapas de exposición subaérea. Estas y otras características sugieren que estos estromatolitos crecieron en ambientes de baja energía, intermareales altos y supramareales. Están constituidos por una fábrica de micrita-microesparita (con una destacada ausencia de aloquímicos) que constituyen alternancias submilimétricas de laminación densa. Estudios detallados con SEM sobre muestras pulidas revelan una preservación excepcional con morfología alargada, microorganismos tipo cocoide, y abundantes agregados de pirita framboidal. Las bacterias con morfologías alargadas están constituyendo una red irregularmente distribuida de filamentos que oscilan en tamaño desde 150 nm hasta, excepcionalmente, 640 nm en longitud; el diámetro oscila entre 50 nm y 90 nm. Las morfologías subesféricas oscilan entre 70 nm y 89 nm. La presencia de abundantes piritas framboidales es interpretada como resultado de una actividad metabólica de bacterias sulfato-reductoras y la descomposición de materia orgánica

Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

Large enhancement of deuteron polarization with frequency modulated microwaves

We report a large enhancement of 1.7 in deuteron polarization up to values of 0.6 due to frequency modulation of the polarizing microwaves in a two liters polarized target using the method of dynamic nuclear polarization. This target was used during a deep inelastic polarized muon-deuteron scattering experiment at CERN. Measurements of the electron paramagnetic resonance absorption spectra show that frequency modulation gives rise to additional microwave absorption in the spectral wings. Although these results are not understood theoretically, they may provide a useful testing ground for the deeper understanding of dynamic nuclear polarization.Comment: 10 pages, including the figures coming in uuencoded compressed tar files in poltar.uu, which also brings cernart.sty and crna12.sty files neede

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Genetic characterization of cassava (Manihot esculenta) landraces in Brazil assessed with simple sequence repeats

Based on nine microsatellite loci, the aim of this study was to appraise the genetic diversity of 42 cassava (Manihot esculenta) landraces from selected regions in Brazil, and examine how this variety is distributed according to origin in several municipalities in the states of Minas Gerais, São Paulo, Mato Grosso do Sul, Amazonas and Mato Grosso. High diversity values were found among the five above-mentioned regions, with 3.3 alleles per locus on an average, a high percentage of polymorphic loci varying from 88.8% to 100%, an average of 0.265 for observed heterozygosity and 0.570 for gene diversity. Most genetic diversity was concentrated within the regions themselves (HS = 0.52). Cluster analysis and principal component based scatter plotting showed greater similarity among landraces from São Paulo, Mato Grosso do Sul and Amazonas, whereas those from Minas Gerais were clustered into a sub-group within this group. The plants from Mato Grosso, mostly collected in the municipality of General Carneiro, provided the highest differentiation. The migration of human populations is one among the possible reasons for this closer resemblance or greater disparity among plants from the various regions

Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications

BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (VT) size was 500 ml, or 7 to 9 ml kg1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P < 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P < 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high VT and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome

Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications: LAS VEGAS - An observational study in 29 countries

BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (V T) size was 500 ml, or 7 to 9 ml kg−1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P ˂ 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P ˂ 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high V T and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome.</p