675 research outputs found
Transitions in the morphological features, habitat use, and diet of young-of-the-year goosefish (Lophius americanus)
This study was designed to improve our understanding of transitions in the early life history and the distribution, habitat use, and diets for young-of-the-year (YOY) goosefish
(Lophius americanus) and, as a result, their role in northeastern U.S. continental shelf ecosystems. Pelagic juveniles (>12 to ca. 50 mm total length [TL]) were distributed over most portions of the continental shelf in the Middle Atlantic Bight, Georges Bank, and into the Gulf of Maine. Most individuals settled by 50â85 mm TL and reached approximately 60â120 mm TL by one year of age. Pelagic YOY fed on chaetognaths, hyperiid amphipods, calanoid copepods, and ostracods, and benthic YOY had a varied diet of fishes and benthic crustaceans. Goosefish are
widely scattered on the continental shelf in the Middle Atlantic Bight during their early life history and once settled, are habitat generalists, and thus play a role in many continental shelf habi
Ultrashort pulse characterization by spectral shearing interferometry with spatially chirped ancillae
We report a new version of spectral phase interferometry for direct electric
field reconstruction (SPIDER), which enables consistency checking through the
simultaneous acquisition of multiple shears and offers a simple and precise
calibration method. By mixing the test pulse with two spatially chirped ancilla
fields we generate a single-shot interferogram which contains multiple shears,
the spectral amplitude of the test pulse, and the reference phase, which is
accurate for broadband pulses. All calibration parameters - shear,
upconversion-frequency and reference phase position - can be accurately
obtained from a single calibration trace.Comment: 11 pages, 7 figure
Self-referenced characterization of space-time couplings in near single-cycle laser pulses
We report on the characterization of space-time couplings in high energy
sub-2-cycle 770nm laser pulses using a self-referencing single-shot method.
Using spatially-encoded arrangement filter-based spectral phase interferometry
for direct electric field reconstruction (SEA-F-SPIDER) we characterize
few-cycle pulses with a wave-front rotation of 2.8x?10^11 rev/sec (1.38 mrad
per half-cycle) and pulses with pulse front tilts ranging from to -0.33 fs/um
to -3.03 fs/um.Comment: 6 pages, 6 figure
Optimisation of Quantum Trajectories Driven by Strong-field Waveforms
Quasi-free field-driven electron trajectories are a key element of
strong-field dynamics. Upon recollision with the parent ion, the energy
transferred from the field to the electron may be released as attosecond
duration XUV emission in the process of high harmonic generation (HHG). The
conventional sinusoidal driver fields set limitations on the maximum value of
this energy transfer, and it has been predicted that this limit can be
significantly exceeded by an appropriately ramped-up cycleshape. Here, we
present an experimental realization of such cycle-shaped waveforms and
demonstrate control of the HHG process on the single-atom quantum level via
attosecond steering of the electron trajectories. With our optimized optical
cycles, we boost the field-ionization launching the electron trajectories,
increase the subsequent field-to-electron energy transfer, and reduce the
trajectory duration. We demonstrate, in realistic experimental conditions, two
orders of magnitude enhancement of the generated XUV flux together with an
increased spectral cutoff. This application, which is only one example of what
can be achieved with cycle-shaped high-field light-waves, has farreaching
implications for attosecond spectroscopy and molecular self-probing
Measuring sub-Planck structural analogues in chronocyclic phase space
The phase space structure of certain quantum states reveals structure on a
scale that is small compared to the Planck area. Using an analog between the
wavefunction of a single photon and the electric field of a classical
ultrashort optical pulse we show that spectral shearing interferometry enables
measurement of such structures directly. Thereby extending the idea of
Praxmeyer et al. In particular, we use multiple-shear spectral interferometry
to fully characterize a pulse consisting of two sub-pulses which are temporally
and spectrally disjoint, without a relative-phase ambiguity. This enables us to
compute the Wigner distribution of the pulse. This spectrographic
representation of the pulse field features fringes that are tilted with respect
to both the time- and frequency axes, showing that in general the shortest
sub-Planck distances may not be in the directions of the canonical (and easily
experimentally accessible) directions. Further, independent of this
orientation, evidence of the sub-Planck scale of the structure maybe extracted
directly from the measured signal.Comment: 7 pages, 7 figures, "Quo vadis Quantum Optics"- special issue of
Optics Communications in memory of Krzysztof Wodkiewic
Effects of 8 weeks of CPAP on lipid-based oxidative markers in obstructive sleep apnea: a randomized trial
Dyslipidaemia and increased oxidative stress have been reported in severe obstructive sleep apnea, and both may be related to the development of cardiovascular disease. We have previously shown in a randomized crossover study in patients with moderate to severe obstructive sleep apnea that therapeutic continuous positive airway pressure treatment for 8 weeks improved postprandial triglycerides and total cholesterol when compared with sham continuous positive airway pressure. From this study we have now compared the effect of 8 weeks of therapeutic continuous positive airway pressure and sham continuous positive airway pressure on oxidative lipid damage and plasma lipophilic antioxidant levels. Unesterified cholesterol, esterified unsaturated fatty acids (cholesteryl linoleate: C18:2; and cholesteryl arachidonate: C20:4; the major unsaturated and oxidizable lipids in low-density lipoproteins), their corresponding oxidized products [cholesteryl ester-derived lipid hydroperoxides and hydroxides (CE-O(O)H)] and antioxidant vitamin E were assessed at 20:30 hours before sleep, and at 06:00 and 08:30 hours after sleep. Amongst the 29 patients completing the study, three had incomplete or missing [CE-O(O)H] data. The mean apnea -hypopnoea index, age and body mass index were 38 per hour, 49 years and 32 kg m(-2) , respectively. No differences in lipid-based oxidative markers or lipophilic antioxidant levels were observed between the continuous positive airway pressure and sham continuous positive airway pressure arms at any of the three time-points [unesterified cholesterol 0.01 mm, P > 0.05; cholesteryl linoleate: C18:2 0.05 mm, P > 0.05; cholesteryl arachidonate: C20:4 0.02 mm, P = 0.05; CE-O(O)H 2.5 nm, P > 0.05; and lipid-soluble antioxidant vitamin E 0.03 ÎŒm, P > 0.05]. In this study, accumulating CE-O(O)H, a marker of lipid oxidation, does not appear to play a role in oxidative stress in obstructive sleep apnea.National Health and Medical Research Council project grant 30193
Evidence and patterns of tuna spawning inside a large no-take marine protected area
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hernandez, C. M., Witting, J., Willis, C., Thorrold, S. R., Llopiz, J. K., & Rotjan, R. D. Evidence and patterns of tuna spawning inside a large no-take marine protected area. Scientific Reports, 9(1), (2019): 10772, doi:10.1038/s41598-019-47161-0.The Phoenix Islands Protected Area (PIPA), one of the worldâs largest marine protected areas, represents 11% of the exclusive economic zone of the Republic of Kiribati, which earns much of its GDP by selling tuna fishing licenses to foreign nations. We have determined that PIPA is a spawning area for skipjack (Katsuwonus pelamis), bigeye (Thunnus obesus), and yellowfin (Thunnus albacares) tunas. Our approach included sampling larvae on cruises in 2015â2017 and using a biological-physical model to estimate spawning locations for collected larvae. Temperature and chlorophyll conditions varied markedly due to observed ENSO states: El Niño (2015) and neutral (2016â2017). However, larval tuna distributions were similar amongst years. Generally, skipjack larvae were patchy and more abundant near PIPAâs northeast corner, while Thunnus larvae exhibited lower and more even abundances. Genetic barcoding confirmed the presence of bigeye (Thunnus obesus) and yellowfin (Thunnus albacares) tuna larvae. Model simulations indicated that most of the larvae collected inside PIPA in 2015 were spawned inside, while stronger currents in 2016 moved more larvae across PIPAâs boundaries. Larval distributions and relative spawning output simulations indicated that both focal taxa spawned inside PIPA in all 3 study years, demonstrating that PIPA is protecting viable tuna spawning habitat.Funding and support was provided by the PIPA Trust, Waitt and Oceans5 Foundations, Sea Education Association, the Prince Albert of Monaco Foundation II, New England Aquarium, and Boston University to R.R. and J.W. C.H. was additionally supported by a National Science Foundation Graduate Research Fellowship. J.L. was additionally supported by NOAA through the Cooperative Institute for the North Atlantic Region (CINAR) under Cooperative Agreement NA14OAR4320158 in the form a CINAR Fellow Award, as well as by the WHOI Academic Programs Office. We thank A. Breef-Pilz for onboard sampling assistance, as well as S. Glancy, J. Pringle, E. Martin, J. Fisher, H. Goss, J. Jaskiel, S. Sheehan, and C. Moller for lab assistance. We thank the PIPA Trust and the PIPA Implementation Office for their support, as well as on-ship Kiribati Observers for their support and assistance: Tekeua Auatabu, Iannang Teaioro, Toaea Beiateuea, Taremon Korere, Kareati Waysang, and Moamoa Kabuati. We thank Q. Hanich for reading sections of this paper in advance. This research was conducted under Kiribati and PIPA permits PRP #s 3/17, 1/16, and 2/15 to JW
Dietary fatty acids and mortality risk from heart disease in US adults: an analysis based on NHANES
We investigated the association of dietary intake of major types of fatty acids with heart disease mortality in a general adult cohort with or without a prior diagnosis of myocardial infarction (MI). This cohort study included US adults who attended the National Health and Nutrition Examination Surveys from 1988 to 2014. Heart disease mortality was ascertained by linkage to the National Death Index records through 31 December 2015. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of fatty acid intake for heart disease mortality. This cohort included 45,820 adults among which 1,541 had a prior diagnosis of MI. Participants were followed up for 532,722 person-years (mean follow-up, 11.6 years), with 2,313 deaths recorded from heart disease being recorded. Intake of saturated (SFAs) and monounsaturated fatty acids (MUFAs) was associated with heart disease mortality after adjustment for all the tested confounders. In contrast, a 5% higher calorie intake from polyunsaturated fatty acids (PUFAs) was associated with a 9% (HR, 0.91; 95% CI 0.83â1.00; Pâ=â0.048) lower multivariate-adjusted risk of heart disease mortality. Sub-analyses showed that this inverse association was present in those without a prior diagnosis of MI (HR,0.89; 95% CI 0.80â0.99) but not in those with the condition (HR, 0.94; 95% CI 0.75â1.16). The lack of association in the MI group could be due to a small sample size or severity and procedural complications (e.g., stenting and medication adherence) of the disease. Higher PUFA intake was associated with a favourable lipid profile. However, further adjustment for plasma lipids did not materially change the inverse association between PUFAs and heart disease mortality. Higher intake of PUFAs, but not SFAs and MUFAs, was associated with a lower adjusted risk of heart disease mortality in a large population of US adults supporting the need to increase dietary PUFA intake in the general public
Attosecond physics at the nanoscale
Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds, which is comparable with the optical field. On the other hand, the second branch involves the manipulation and engineering of mesoscopic systems, such as solids, metals and dielectrics, with nanometric precision. Although nano-engineering is a vast and well-established research field on its own, the merger with intense laser physics is relatively recent. In this article we present a comprehensive experimental and theoretical overview of physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures. In particular we elucidate how the spatially inhomogeneous laser induced fields at a nanometer scale modify the laser-driven electron dynamics. Consequently, this has important impact on pivotal processes such as ATI and HHG. The deep understanding of the coupled dynamics between these spatially inhomogeneous fields and matter configures a promising way to new avenues of research and applications. Thanks to the maturity that attosecond physics has reached, together with the tremendous advance in material engineering and manipulation techniques, the age of atto-nano physics has begun, but it is in the initial stage. We present thus some of the open questions, challenges and prospects for experimental confirmation of theoretical predictions, as well as experiments aimed at characterizing the induced fields and the unique electron dynamics initiated by them with high temporal and spatial resolution
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