Características de las secuencias deposicionales de alta frecuencia en el sistema arrecifal del Mioceno superior de Mallorca

Application of sequence stratigraphy concepts in well-exposed prograding carbonate complexes, such as the example of Mallorca, shows marked peculiarities differing from the commonly used as standard model of the Exxon group. These peculiarities are seen in high-frequency sequences bounded by well-definederosion surfaces. The standard model is incomplete in the sense that it shows no sedimentary record of the fall of the sea-level cycle, except for erosion or karstification. In contrast, the Mallorcan example shows more complete and continuous sedimentary record during the entire sea-level cycle: an offlapping package, commonly ignored or misinterpreted, is deposited during the internal of sea-level fall, and considered as a new systems tract. As a result, the most obvious and marked erosion surface separating these high-frequency packages is the sequence boundary. Furthermore, in the standard model the downlap surface is correlative with the maximum flooding surface and a condensed section. In contrast, the Mallorcan model shows that a condensed section and downlap surface are produced during the offlapping systems tract, whereas the maximum flooding surface are indistinct. There are two surfaces easily recognized in the Mallorcan example: an erosion surface and a downlap surface. On this basis there are two major systems packages or tracts: a lower package with aggradation in all the systems formed during sea-level rise and high-stillstand and an upper package with offlapping progradation formed during sea-level fall and low-stillstand. Al1 the above peculiarities of the Mallorcan prograding reef complex show the need for careful application of the dynamic concepts of sequence stratigraphy, rather than the strict reference to the standard scheme. The relationships between carbonate production and each segment of the sea-level cycle explain these departures from the standard 3rd-order sequencemodel developed from siliciclastic deposits on passive margins

Características de las secuencias deposicionales de alta frecuencia en el sistema arrecifal del Mioceno superior de Mallorca

Application of sequence stratigraphy concepts in well-exposed prograding carbonate complexes, such as the example of Mallorca, shows marked peculiarities differing from the commonly used as standard model of the Exxon group. These peculiarities are seen in high-frequency sequences bounded by well-definederosion surfaces. The standard model is incomplete in the sense that it shows no sedimentary record of the fall of the sea-level cycle, except for erosion or karstification. In contrast, the Mallorcan example shows more complete and continuous sedimentary record during the entire sea-level cycle: an offlapping package, commonly ignored or misinterpreted, is deposited during the internal of sea-level fall, and considered as a new systems tract. As a result, the most obvious and marked erosion surface separating these high-frequency packages is the sequence boundary. Furthermore, in the standard model the downlap surface is correlative with the maximum flooding surface and a condensed section. In contrast, the Mallorcan model shows that a condensed section and downlap surface are produced during the offlapping systems tract, whereas the maximum flooding surface are indistinct. There are two surfaces easily recognized in the Mallorcan example: an erosion surface and a downlap surface. On this basis there are two major systems packages or tracts: a lower package with aggradation in all the systems formed during sea-level rise and high-stillstand and an upper package with offlapping progradation formed during sea-level fall and low-stillstand. Al1 the above peculiarities of the Mallorcan prograding reef complex show the need for careful application of the dynamic concepts of sequence stratigraphy, rather than the strict reference to the standard scheme. The relationships between carbonate production and each segment of the sea-level cycle explain these departures from the standard 3rd-order sequencemodel developed from siliciclastic deposits on passive margins

Information flow and optimization in transcriptional control

In the simplest view of transcriptional regulation, the expression of a gene is turned on or off by changes in the concentration of a transcription factor (TF). We use recent data on noise levels in gene expression to show that it should be possible to transmit much more than just one regulatory bit. Realizing this optimal information capacity would require that the dynamic range of TF concentrations used by the cell, the input/output relation of the regulatory module, and the noise levels of binding and transcription satisfy certain matching relations. This parameter-free prediction is in good agreement with recent experiments on the Bicoid/Hunchback system in the early Drosophila embryo, and this system achieves ~90% of its theoretical maximum information transmission.Comment: 5 pages, 4 figure

Prenatal Diagnosis of Gómez-López-Hernández Syndrome.

Gómez-López-Hernández syndrome (GLHS), also known as cerebello-trigeminal-dermal dysplasia, is an extremely rare neurocutaneous disease, classically described by the triad of rhombencephalosynapsis (RES), bilateral focal alopecia, and trigeminal anesthesia. The clinical and radiographic spectrum of GLHS is now known to be broader, including craniofacial and supratentorial anomalies, as well as neurodevelopmental issues. Here, we present a case of antenatally diagnosed GLHS with RES, hydrocephaly, and craniofacial anomalies identified on ultrasound (low-set ears with posterior rotation, hypertelorism, midface hypoplasia, micrognathia, and anteverted nares) which were confirmed by autopsy after termination of pregnancy at 23 weeks of gestation. As no known genetic causes have been identified and the classical triad is not applicable to prenatal imaging, prenatal diagnosis of GLHS is based on neuroimaging and the identification of supporting features. In presence of an RES associated with craniofacial abnormalities in prenatal (brachycephaly, turricephaly, low-set ears, midface retrusion, micrognathia), GLHS should be considered as "possible" according to postnatal criteria

Temperature and magnetic-field dependence of the conductivity of YBaCuO films in the vicinity of superconducting transition: Effect of Tc-inhomogeneity

Temperature and magnetic field dependences of the conductivity of YBaCuO films in the transition region are analyzed taking into account spatial inhomogeneity in transition temperature, Tc. (i) An expression for the superconducting contribution to conductivity, \sigma_s(T,H,Tc), of a homogeneous superconductor for H<<Hc2(T=0) is obtained using the solution of the Ginzburg-Landau equation in form of perturbation expansions [S.Ullah, A.T.Dorsey, PRB 44, 262 (1991)]. (ii) The error in \sigma_s(T,H,Tc) occurring due to the presence of Tc-inhomogeneity is calculated and plotted on an H-T plane diagram. These calculations use an effective medium approximation and a Gaussian distribution of Tc. (iii) Measuring the temperature dependences of a voltage, induced by a focused electron beam, we determine spatial distributions of the critical temperature for YBaCuO microbridges with a 2 micron resolution. A typical Tc-distribution dispersion is found to be approximately 1K. For such dispersion, error in \sigma_s(T,H,Tc) due to Tc-inhomogeneity exceeds 30% for magnetic fields H < 1 T and temperatures |T-Tc| < 0.5 K. (iv) Experimental R(T,H) dependences of resistance are well described by a numerical solution of a set of Kirchoff equations for the resistor network based on the measured spatial distributions of Tc and the expression for \sigma_s(T,H,Tc).Comment: REVTeX, 12 pages including 7 figures, resubmitted to Phys. Rev.

Critical Dynamics of a Vortex Loop Model for the Superconducting Transition

We calculate analytically the dynamic critical exponent $z_{MC}$ measured in Monte Carlo simulations for a vortex loop model of the superconducting transition, and account for the simulation results. In the weak screening limit, where magnetic fluctuations are neglected, the dynamic exponent is found to be $z_{MC} = 3/2$. In the perfect screening limit, $z_{MC} = 5/2$. We relate $z_{MC}$ to the actual value of $z$ observable in experiments and find that $z \sim 2$, consistent with some experimental results

Quantum interference and Klein tunneling in graphene heterojunctions

The observation of quantum conductance oscillations in mesoscopic systems has traditionally required the confinement of the carriers to a phase space of reduced dimensionality. While electron optics such as lensing and focusing have been demonstrated experimentally, building a collimated electron interferometer in two unconfined dimensions has remained a challenge due to the difficulty of creating electrostatic barriers that are sharp on the order of the electron wavelength. Here, we report the observation of conductance oscillations in extremely narrow graphene heterostructures where a resonant cavity is formed between two electrostatically created bipolar junctions. Analysis of the oscillations confirms that p-n junctions have a collimating effect on ballistically transmitted carriers. The phase shift observed in the conductance fringes at low magnetic fields is a signature of the perfect transmission of carriers normally incident on the junctions and thus constitutes a direct experimental observation of ``Klein Tunneling.''Comment: 13 pages and 6 figures including supplementary information. The paper has been modified in light of new theoretical results available at arXiv:0808.048

Anatomy and origin of authochthonous late Pleistocene forced regression deposits, east Coromandel inner shelf, New Zealand: implications for the development and definition of the regressive systems tract

High-resolution seismic reflection data from the east Coromandel coast, New Zealand, provide details of the sequence stratigraphy beneath an autochthonous, wave dominated inner shelf margin during the late Quaternary (0-140 ka). Since c. 1 Ma, the shelf has experienced limited subsidence and fluvial sediment input, producing a depositional regime characterised by extensive reworking of coastal and shelf sediments during glacio-eustatic sea-level fluctuations. It appears that only one complete fifth-order (c. 100 000 yr) depositional sequence is preserved beneath the inner shelf, the late Pleistocene Waihi Sequence, suggesting any earlier Quaternary sequences were mainly cannibalised into successively younger sequences. The predominantly Holocene-age Whangamata Sequence is also evident in seismic data and modern coastal deposits, and represents an incomplete depositional sequence in its early stages of formation. A prominent aspect of the sequence stratigraphy off parts of the east Coromandel coast is the presence of forced regressive deposits (FRDs) within the regressive systems tract (RST) of the late Pleistocene Waihi Sequence. The FRDs are interpreted to represent regressive barrier-shoreface sands that were sourced from erosion and onshore reworking of underlying Pleistocene sediments during the period of slow falling sea level from isotope stages 5 to 2 (c. 112-18 ka). The RST is volumetrically the most significant depositional component of the Waihi Sequence; the regressive deposits form a 15-20 m thick, sharp-based, tabular seismic unit that downsteps and progrades continuously across the inner shelf. The sequence boundary for the Waihi Sequence is placed at the most prominent, regionally correlative, and chronostratigraphically significant surface, namely an erosional unconformity characterised in many areas by large incised valleys that was generated above the RST. This unconformity is interpreted as a surface of maximum subaerial erosion generated during the last glacial lowstand (c. 18 ka). Although the base of the RST is associated with a prominent regressive surface of erosion, this is not used as the sequence boundary as it is highly diachronous and difficult to identify and correlate where FRDs are not developed. The previous highstand deposits are limited to subaerial barrier deposits preserved behind several modern Holocene barriers along the coast, while the transgressive systems tract is preserved locally as incised-valley fill deposits beneath the regressive surface of erosion at the base of the RST. Many documented late Pleistocene RSTs have been actively sourced from fluvial systems feeding the shelf and building basinward-thickening, often stacked wedges of FRDs, for which the name allochthonous FRDs is suggested. The Waihi Sequence RST is unusual in that it appears to have been sourced predominantly from reworking of underlying shelf sediments, and thus represents an autochthonous FRD. Autochthonous FRDs are also present on the Forster-Tuncurry shelf in southeast Australia, and may be a common feature in other shelf settings with low subsidence and low sediment supply rates, provided shelf gradients are not too steep, and an underlying source of unconsolidated shelf sediments is available to source FRDs. The preservation potential of such autochthonous FRDs in ancient deposits is probably low given that they are likely to be cannibalised during subsequent sea-level falls

Critical scaling of the a.c. conductivity for a superconductor above Tc

We consider the effects of critical superconducting fluctuations on the scaling of the linear a.c. conductivity, \sigma(\omega), of a bulk superconductor slightly above Tc in zero applied magnetic field. The dynamic renormalization- group method is applied to the relaxational time-dependent Ginzburg-Landau model of superconductivity, with \sigma(\omega) calculated via the Kubo formula to O(\epsilon^{2}) in the \epsilon = 4 - d expansion. The critical dynamics are governed by the relaxational XY-model renormalization-group fixed point. The scaling hypothesis \sigma(\omega) \sim \xi^{2-d+z} S(\omega \xi^{z}) proposed by Fisher, Fisher and Huse is explicitly verified, with the dynamic exponent z \approx 2.015, the value expected for the d=3 relaxational XY-model. The universal scaling function S(y) is computed and shown to deviate only slightly from its Gaussian form, calculated earlier. The present theory is compared with experimental measurements of the a.c. conductivity of YBCO near Tc, and the implications of this theory for such experiments is discussed.Comment: 16 pages, submitted to Phys. Rev.

COVID-19-related medicine utilization study in pregnancy: The COVI-PREG cohort

AIM The objective of this study was to describe the use of COVID-19-related medicines during pregnancy and their evolution between the early/late periods of the pandemic. METHODS Pregnant women who tested positive for SARS-CoV-2 from March 2020 to July 2021 were included using the COVI-PREG registry. Exposure to the following COVID-19-related medicines was recorded: antibiotics, antivirals, hydroxychloroquine, corticosteroids, anti-interleukin-6 and immunoglobulins. We described the prevalence of medicines used, by trimester of pregnancy, maternal COVID-19 severity level and early/late period of the pandemic (before and after 1 July 2020). FINDINGS We included 1964 pregnant patients who tested positive for SARS-CoV-2. Overall, 10.4% (205/1964) received at least one COVID-19-related medicine including antibiotics (8.6%; 169/1694), corticosteroids (3.2%; 62/1964), antivirals (2.0%; 39/1964), hydroxychloroquine (1.4%; 27/1964) and anti-interleukin-6 (0.3%; 5/1964). The use of at least one COVID-19-related medicine was 3.1% (12/381) in asymptomatic individuals, 4.2% (52/1233) in outpatients, 19.7% (46/233) in inpatients without oxygen, 72.1% (44/61) in those requiring standard oxygen, 95.7% (22/23) in those requiring high flow oxygen, 96.2% (25/26) in patients who required intubation and 57.1% (4/7) among patients who died. The proportion who received medicines to treat COVID-19 was higher before than after July 2020 (16.7% vs. 7.7%). Antibiotics, antivirals and hydroxychloroquine had lower rates of use during the late period. CONCLUSION Medicine use in pregnancy increased with disease severity. The trend towards increased use of corticosteroids seems to be aligned with changing guidelines. Evidence is still needed regarding the effectiveness and safety of COVID-19-related medicines in pregnancy