Copepods from warm-core ring 82-H

See Supplementary information.txt for information regarding how access and use the files in WHOI-89-24-data.zipNet tows were collected with a Multiple Opening/Closing Net Environmental Sampling System (MOCNESS) carrying twenty 1-m2 nets in October 1982 in and near warm-core ring 82-H in the North Atlantic (RV/Knorr cruise 98). This report includes the species list and abundance tables of the copepods found in five of the tows. There are four types of abundance tables: raw data, standardized to #/1000 m3 , integrated #/m2 to 1000 m depth, and cumulative percents over the depth of the tows.Funding was provided by the National Science Foundation through grant Number OCE 80-12748, OCE 85-08350, OCE 87-09962, OCE 80-19055, and OCE 80-17271

Reply to \u27Do oceanic zooplankton aggregate at, or near, the deep chlorophyll maximum?\u27

We appreciate the time and attention given our paper by Longhurst and Herman and the opportunity to reply to their critique. Unfortunately, we believe their difficulties with the presentation of our data are more subjective than substantive. In fact, we believe a careful reading of our text will show that our conclusions are suitably conservative...

Correction of systematic errors in scanning tunnelling spectra on semiconductor surfaces: the energy gap of Si(111)-7x7 at 0.3 K

The investigation of the electronic properties of semiconductor surfaces using scanning tunnelling spectroscopy (STS) is often hindered by non-equilibrium transport of the injected charge carriers. We propose a correction method for the resulting systematic errors in STS data, which is demonstrated for the well known Si(111)-(7x7) surface. The surface has an odd number of electrons per surface unit cell and is metallic above 20 K. We observe an energy gap in the ground state of this surface by STS at 0.3 K. After correction, the measured width of the gap is (70 +- 15) meV which is compatible with previous less precise estimates. No sharp peak of the density of states at the Fermi level is observed, in contrast to proposed models for the Si(111)-(7x7) surface.Comment: 10 pages, 4 figure

Habitat usage by the cryptic copepods Pseudocalanus moultoni and P. newmani on Georges Bank (Northwest Atlantic)

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Continental Shelf Research 111 (2015): 83-94, doi:10.1016/j.csr.2015.11.001.The cryptic copepod species, Pseudocalanus moultoni and P. newmani, co-occur on Georges Bank and in the Gulf of Maine (Northwest Atlantic); even recent studies have reported results and conclusions based on examination of the combined species. Species-specific PCR (SS-PCR) based on mitochondrial cytochrome oxidase I (COI) sequence divergence was used in this study to discriminate the species. Species-specific descriptions of habitat usage and predicted patterns of transport and retention on Georges Bank were made by mapping distributions and calculating abundances of each species from January to June, 1999 for four vertical strata (0-15 m, 15-40 m, 40-100 m, and 0-100 m) and five regions (Northern Flank, Bank Crest, Northeast Peak, Southern Flank, and Slope Water) identified on the basis of bathymetry and circulation. Patterns of distribution and abundance for the two species during January to June, 1999 were largely consistent with those described based on vertically integrating mapping and analysis for the same period in 1997 by McGillicuddy and Bucklin (2002). The region-specific and depth-stratified analyses allowed further discrimination in habitat usage by the species and confirmed the distinctive patterns for the two species. The observed differences between the species in abundances among the five regions and three depth strata over Georges Bank impact their transport trajectories. The concentration of P. moultoni in deep layers likely explains the higher rates of retention and lower rates of advective loss of this species from the Bank, compared to P. newmani, which may be more subject to wind-driven transport in the surface layer. Accurate identification and discrimination of even closely-related and cryptic species is needed to ensure full understanding and realistic predictions of changes in diversity of zooplankton and the functioning of pelagic ecosystems.Funding was provided by the National Science Foundation as part of the U.S. GLOBEC Program (Award Nos. OCE-9529100 and OCE-9632840 to Ann Bucklin; Award No. OCE-0815047 to Dennis McGillicuddy)

Circular Polarization of Circumstellar Water Masers around S Per

We present the first circular polarization measurements of circumstellar H2O masers. Previously the magnetic field in circumstellar envelopes has been estimated using polarization observations of SiO and OH masers. SiO masers are probes of the high temperature and density regime close to the central star. OH masers are found at much lower densities and temperatures, generally much further out in the circumstellar envelope. The detection of the circular polarization of the (6_16 - 5_23) rotational transition of the H2O maser could be attributed to Zeeman splitting due to the magnetic field in the intermediate temperature and density regime. The fields inferred here agree well with predicted values for a combination of the r^{-2} dependence of a solar-type magnetic field, and the coupling of the field to the high density masing regions. We also discuss the unexpected narrowing of the circular polarization spectrum.Comment: 4 pages, 4 figures; accepted for publication in Astronomy and Astrophysics Letter

Phase behaviour of the quantum Lennard-Jones solid

The Lennard-Jones potential is perhaps one of the most widely-used models for the interaction of uncharged particles, such as noble gas solids. The phase diagram of the classical LJ solid is known to exhibit transitions between hcp and fcc phases. However, the phase behaviour of the quantum Lennard-Jones solid remains unknown. Thermodynamic integration based on path integral molecular dynamics and lattice dynamics calculations are used to study the phase stability of the hcp and fcc Lennard-Jones solids. The hcp phase is shown to be stabilized by quantum effects in PIMD while fcc is shown to be favoured by lattice dynamics, which suggests a possible re-entrant low pressure hcp phase for highly quantum systems. Implications for the phase stability of noble gas solids are discussed. For parameters equating to Helium, the expansion due to zero-point vibrations is associated with quantum melting: neither crystal structure is stable at zero pressure

Two inequivalent sublattices and orbital ordering in MnV2O4 studied by 51V NMR

We report detailed 51V NMR spectra in a single crystal of MnV2O4. The vanadium spectrum reveals two peaks in the orbitally ordered state, which arise from different internal hyperfine fields at two different V sublattices. These internal fields evolve smoothly with externally applied field, and show no change in structure that would suggest a change of the orbital ordering. The result is consistent with the orbital ordering model recently proposed by Sarkar et al. [Phys. Rev. Lett. 102, 216405 (2009)] in which the same orbital that is a mixture of t_2g orbitals rotates by about 45$^\circ$ alternately within and between orbital chains in the I4_1/a tetragonal space group.Comment: 4 pages, 4 figures, title changed, published in PRB as a rapid com

Biological control of the vernal population increase of \u3cem\u3eCalanus finmarchicus\u3c/em\u3e on Georges Bank

An adjoint data assimilation approach was used to quantify the physical and biological controls on Calanus finmarchicus N3–C6 stages on Georges Bank and its nearby environs. The mean seasonal cycle of vertically averaged distributions, from 5 years of the GLOBEC Georges Bank Broad-Scale Surveys between January and June, was assimilated into a physical–biological model based on the climatological circulation. Large seasonal and spatial variability is present in the inferred supply sources, mortality rates, computed molting fluxes, and physical transports. Estimated mortalities fall within the range of observed rates, and exhibit stage structure that is consistent with earlier findings. Inferred off-bank initial conditions indicate that the deep basins in the Gulf of Maine are source regions of early stage nauplii and late-stage copepodids in January. However, the population increase on Georges Bank from January to April is controlled mostly by local biological processes. Magnitudes of the physical transport terms are nearly as large as the mortality and molting fluxes, but their bank-wide averages are small in comparison to the biological terms. The hypothesis of local biological control is tested in a sensitivity experiment in which upstream sources are set to zero. In that solution, the lack of upstream sources is compensated by a decrease in mortality that is much smaller than the uncertainty in observational estimates