Seismic data reveal eastern Black Sea Basin structure

Rifted continental margins are formed by progressive extension of the lithosphere. The development of these margins plays an integral role in the plate tectonic cycle, and an understanding of the extensional process underpins much hydrocarbon exploration. A key issue is whether the lithosphere extends uniformly, or whether extension varies\ud with depth. Crustal extension may be determined using seismic techniques. Lithospheric extension may be inferred from the waterloaded subsidence history, determined from\ud the pattern of sedimentation during and after rifting. Unfortunately, however, many rifted margins are sediment-starved, so the subsidence history is poorly known.\ud To test whether extension varies between the crust and the mantle, a major seismic experiment was conducted in February–March 2005 in the eastern Black Sea Basin (Figure 1), a deep basin where the subsidence history is recorded\ud by a thick, post-rift sedimentary sequence. The seismic data from the experiment indicate the presence of a thick, low-velocity zone, possibly representing overpressured sediments. They also indicate that the basement and\ud Moho in the center of the basin are both several kilometers shallower than previously inferred. These initial observations may have considerable impact on thermal models of the petroleum system in the basin. Understanding\ud the thermal history of potential source rocks is key to reducing hydrocarbon exploration risk. The experiment, which involved collaboration between university groups in the United Kingdom, Ireland, and Turkey, and BP and\ud Turkish Petroleum (TPAO), formed part of a larger project that also is using deep seismic reflection and other geophysical data held by the industry partners to determine the subsidence history and hence the strain evolution of\ud the basin

A 5000-year record of relative sea-level change in New Jersey, USA

Stratigraphic data from salt marshes provide accurate reconstructions of Holocene relative sea level (RSL) change and necessary constraints to models of glacial isostatic adjustment (GIA), which is the dominant cause of late Holocene RSL rise along the U.S. mid-Atlantic coast. Here, we produce a new mid- to late-Holocene RSL record from a salt marsh bordering Great Bay in southern New Jersey using basal peats. We use a multi-proxy approach (foraminifera and geochemistry) to identify the indicative meaning of the basal peats and produce sea-level index points (SLIPs) that include a vertical uncertainty for tidal range change and sediment compaction and a temporal uncertainty based on high precision Accelerator Mass Spectrometry radiocarbon dating of salt-marsh plant macrofossils. The 14 basal SLIPs range from 1211 ± 56 years BP to 4414 ± 112 years BP, which we combine with published RSL data from southern New Jersey and use with a spatiotemporal statistical model to show that RSL rose 8.6 m at an average rate of 1.7 ± 0.1 mm/yr (1σ) from 5000 years BP to present. We compare the RSL changes with an ensemble of 1D (laterally homogenous) and site-specific 3D (laterally heterogeneous) GIA models, which tend to overestimate the magnitude of RSL rise over the last 5000 years. The continued discrepancy between RSL data and GIA models highlights the importance of using a wide array of ice model and viscosity model parameters to more precisely fit site-specific RSL data along the U.S. mid-Atlantic coast

A realistic example of chaotic tunneling: The hydrogen atom in parallel static electric and magnetic fields

Statistics of tunneling rates in the presence of chaotic classical dynamics is discussed on a realistic example: a hydrogen atom placed in parallel uniform static electric and magnetic fields, where tunneling is followed by ionization along the fields direction. Depending on the magnetic quantum number, one may observe either a standard Porter-Thomas distribution of tunneling rates or, for strong scarring by a periodic orbit parallel to the external fields, strong deviations from it. For the latter case, a simple model based on random matrix theory gives the correct distribution.Comment: Submitted to Phys. Rev.

Quantum Convolutional Coding with Shared Entanglement: General Structure

We present a general theory of entanglement-assisted quantum convolutional coding. The codes have a convolutional or memory structure, they assume that the sender and receiver share noiseless entanglement prior to quantum communication, and they are not restricted to possess the Calderbank-Shor-Steane structure as in previous work. We provide two significant advances for quantum convolutional coding theory. We first show how to "expand" a given set of quantum convolutional generators. This expansion step acts as a preprocessor for a polynomial symplectic Gram-Schmidt orthogonalization procedure that simplifies the commutation relations of the expanded generators to be the same as those of entangled Bell states (ebits) and ancilla qubits. The above two steps produce a set of generators with equivalent error-correcting properties to those of the original generators. We then demonstrate how to perform online encoding and decoding for a stream of information qubits, halves of ebits, and ancilla qubits. The upshot of our theory is that the quantum code designer can engineer quantum convolutional codes with desirable error-correcting properties without having to worry about the commutation relations of these generators.Comment: 23 pages, replaced with final published versio

Sociodemographic, health behavioral, and clinical risk factors for anotia/microtia in a population-based case-control study

Objective: Anotia and microtia are congenital malformations of the external ear with few known risk factors. We conducted a comprehensive assessment of a wide range of potential risk factors using data from the National Birth Defects Prevention Study (NBDPS), a population-based case-control study of non-chromosomal structural birth defects in the United States. Methods: Mothers of 699 infants with anotia or microtia (cases) and 11,797 non-malformed infants (controls) delivered between 1997 and 2011 were interviewed to obtain information about sociodemographic, health behavioral, and clinical characteristics. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated with logistic regression. Results: Infants with anotia/microtia were more likely to be male (aOR, 1.29; 95% CI, 1.10–1.50) and from a multifetal pregnancy (aOR, 1.68; 95% CI, 1.16–2.42). Cases were also more likely to have parents of Hispanic ethnicity (maternal aOR, 3.19; 95% CI, 2.61–3.91; paternal aOR, 2.11; 95% CI, 1.54–2.88), and parents born outside the United States (maternal aOR, 1.29; 95% CI, 1.06–1.57; paternal aOR, 1.92; 95% CI, 1.53–2.41). Maternal health conditions associated with increased odds of anotia/microtia included obesity (aOR, 1.31; 95% CI, 1.06–1.61) and pre-pregnancy diabetes (type I aOR, 9.89; 95% CI, 5.46–17.92; type II aOR, 4.70; 95% CI, 2.56–8.63). Reduced odds were observed for black mothers (aOR, 0.57; 95% CI, 0.38–0.85) and mothers reporting daily intake of folic acid-containing supplements (aOR, 0.59; 95% CI, 0.46–0.76). Conclusion: We identified several risk factors for anotia/microtia, some which have been previously reported (e.g., diabetes) and others which we investigate for perhaps the first time (e.g., binge drinking) that warrant further investigation. Our findings point to some potentially modifiable risk factors and provide further leads toward understanding the etiology of anotia/microtia

Quantification of selection bias in studies of risk factors for birth defects among livebirths

Background: Risk factors for birth defects are frequently investigated using data limited to liveborn infants. By conditioning on survival, results of such studies may be distorted by selection bias, also described as “livebirth bias.” However, the implications of livebirth bias on risk estimation remain poorly understood. Objectives: We sought to quantify livebirth bias and to investigate the conditions under which it arose. Methods: We used data on 3994 birth defects cases and 11 829 controls enrolled in the National Birth Defects Prevention Study to compare odds ratio (OR) estimates of the relationship between three established risk factors (antiepileptic drug use, smoking, and multifetal pregnancy) and four birth defects (anencephaly, spina bifida, omphalocele, and cleft palate) when restricted to livebirths as compared to among livebirths, stillbirths, and elective terminations. Exposures and birth defects represented varying strengths of association with livebirth; all controls were liveborn. We performed a quantitative bias analysis to evaluate the sensitivity of our results to excluding terminated and stillborn controls. Results: Cases ranged from 33% liveborn (anencephaly) to 99% (cleft palate). Smoking and multifetal pregnancy were associated with livebirth among anencephaly (crude OR [cOR] 0.61 and cOR 3.15, respectively) and omphalocele cases (cOR 2.22 and cOR 5.22, respectively). For analyses of the association between exposures and birth defects, restricting to livebirths produced negligible differences in estimates except for anencephaly and multifetal pregnancy, which was twofold higher among livebirths (adjusted OR [aOR] 4.93) as among all pregnancy outcomes (aOR 2.44). Within tested scenarios, bias analyses suggested that results were not sensitive to the restriction to liveborn controls. Conclusions: Selection bias was generally limited except for high mortality defects in the context of exposures strongly associated with livebirth. Findings indicate that substantial livebirth bias is unlikely to affect studies of risk factors for most birth defects

Associations between PM2.5 and risk of preterm birth among liveborn infants

Purpose: Studies suggest exposure to ambient particulate matter less than 2.5 μg/m3 in aerodynamic diameter (PM2.5) may be associated with preterm birth (PTB), but few have evaluated how this is modified by ambient temperature. We investigated the relationship between PM2.5 exposure during pregnancy and PTB in infants without birth defects (1999–2006) and enrolled in the National Birth Defects Prevention Study and how it is modified by concurrent temperature. Methods: PTB was defined as spontaneous or iatrogenic delivery before 37 weeks. Exposure was assigned using inverse distance weighting with up to four monitors within 50 kilometers of maternal residence. To account for state-level variations, a Bayesian two-level hierarchal model was developed. Results: PTB was associated with PM2.5 during the third and fourth months of pregnancy (range: (odds ratio (95% confidence interval) = 1.00 (0.35, 2.15) to 1.49 (0.82, 2.68) and 1.31 (0.56, 2.91) to 1.62 (0.7, 3.32), respectively); no week of exposure conveyed greater risk. Temperature may modify this relationship; higher local average temperatures during pregnancy yielded stronger positive relationships between PM2.5 and PTB compared to nonstratified results. Conclusions: Results add to literature on associations between PM2.5 and PTB, underscoring the importance of considering co-exposures when estimating effects of PM2.5 exposure during pregnancy

Observation of exclusive DVCS in polarized electron beam asymmetry measurements

We report the first results of the beam spin asymmetry measured in the reaction e + p -> e + p + gamma at a beam energy of 4.25 GeV. A large asymmetry with a sin(phi) modulation is observed, as predicted for the interference term of Deeply Virtual Compton Scattering and the Bethe-Heitler process. The amplitude of this modulation is alpha = 0.202 +/- 0.028. In leading-order and leading-twist pQCD, the alpha is directly proportional to the imaginary part of the DVCS amplitude.Comment: 6 pages, 5 figure