The Peierls substitution in an engineered lattice potential

Artificial gauge fields open new possibilities to realize quantum many-body systems with ultracold atoms, by engineering Hamiltonians usually associated with electronic systems. In the presence of a periodic potential, artificial gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here, we describe a one-dimensional lattice derived purely from effective Zeeman-shifts resulting from a combination of Raman coupling and radiofrequency magnetic fields. In this lattice, the tunneling matrix element is generally complex. We control both the amplitude and the phase of this tunneling parameter, experimentally realizing the Peierls substitution for ultracold neutral atoms.Comment: 6 pages, 5 figure

Quantum phase transition to unconventional multi-orbital superfluidity in optical lattices

Orbital physics plays a significant role for a vast number of important phenomena in complex condensed matter systems such as high-T$_c$ superconductivity and unconventional magnetism. In contrast, phenomena in superfluids -- especially in ultracold quantum gases -- are commonly well described by the lowest orbital and a real order parameter. Here, we report on the observation of a novel multi-orbital superfluid phase with a {\it complex} order parameter in binary spin mixtures. In this unconventional superfluid, the local phase angle of the complex order parameter is continuously twisted between neighboring lattice sites. The nature of this twisted superfluid quantum phase is an interaction-induced admixture of the p-orbital favored by the graphene-like band structure of the hexagonal optical lattice used in the experiment. We observe a second-order quantum phase transition between the normal superfluid (NSF) and the twisted superfluid phase (TSF) which is accompanied by a symmetry breaking in momentum space. The experimental results are consistent with calculated phase diagrams and reveal fundamentally new aspects of orbital superfluidity in quantum gas mixtures. Our studies might bridge the gap between conventional superfluidity and complex phenomena of orbital physics.Comment: 5 pages, 4 figure

Refining the Moose Serum Progesterone Threshold to Diagnose Pregnancy

Pregnancy determination is necessary for sound wildlife management and understanding population dynamics. Pregnancy rates are sensitive to environmental and physiological factors and may indicate the overall trajectory of a population. Pregnancy can be assessed through direct methods (rectal palpation, sonography) or indicated using hormonal assays (serum progesterone or pregnancy-specific protein B, fecal progestogen metabolites). A commonly used threshold of 2 ng/ml of progesterone in serum has been used by moose biologists to indicate pregnancy but has not been rigorously investigated. To refine this threshold, we examined the relationship between progesterone concentrations in serum samples and pregnancy in 87 moose (Alces alces; 64 female, 23 male) captured from 2010 to 2020 in the Grand Portage Indian Reservation in northeastern Minnesota, USA. Pregnancy was confirmed via rectal palpation (n = 25), necropsy (n = 2), calf observation (n = 25) or characteristic pre-calving behavior (n = 6), with a total of 58 females determined pregnant and 6 not pregnant; 23 males were included to increase the non-pregnant sample size. Using receiver operating characteristic analysis, we identified an optimal threshold of 1.115 ng/ml with a specificity of 0.97 (95% confidence interval [CI] = 0.90–1.00) and a sensitivity of 0.98 (95% CI = 0.95–1.00). Progesterone concentrations were significantly higher in cases of pregnant versus non-pregnant cows, but we did not detect a difference between single and twin births. We applied our newly refined threshold to calculate annual pregnancy rates for all female moose (n = 133) captured in Grand Portage from 2010 to 2021. Mean pregnancy rate during this period was 91% and ranged annually from 69.2 to 100%. Developing a reliable method for determining pregnancy status via serum progesterone analyses will allow wildlife managers to assess pregnancy rates of moose without devoting substantial time and resources to palpation and calf monitoring

Discerning primary versus diagenetic signals in carbonate carbon and oxygen isotope records: An example from the Permian-Triassic boundary of Iran

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordSedimentary successions across the Permian-Triassic boundary (PTB) are marked by a prominent negative carbon isotope excursion. This excursion, found in both fossil (e.g., brachiopod) and bulk carbonate at many sites around the world, is generally considered to be related to a global carbon cycle perturbation. Oxygen isotopes also show a negative excursion across the PTB, but because δ18O is more prone to diagenetic overprint (especially in bulk carbonate), these data are often not used in palaeoenvironmental analyses. In the present study, bulk-rock and brachiopod δ13C and δ18O, as well as conodont δ18O, were analyzed in PTB successions at Kuh-e-Ali Bashi and Zal (NW Iran) in order to evaluate diagenetic overprints on primary marine isotopic signals. The results show that the use of paired C-O isotopes and Mn-Sr concentrations is not sufficient to identify diagenetic alteration in bulk materials, because δ13C-δ18O covariation can be due to environmental factors rather than diagenesis, and Sr/Ca and Mn/Ca ratios can vary as a function of bulk-rock lithology. Comparison of δ13C profiles shows that all bulk carbonate is altered to some degree, although the general bulk-rock trend mimics that of the brachiopod data with a systematic offset of -1.2(±0.4)‰. This suggests that the first-order δ13C trend in bulk carbonate is generally robust but that the significance of small-scale carbon isotope fluctuations is uncertain, especially when such fluctuations are linked to lithologic variation. The PTB interval, which is marked by a low-carbonate 'Boundary Clay' in the study sections, may be especially prone to diagenetic alteration, e.g., via late-stage dolomitization. Comparison of oxygen-isotope profiles for bulk rock and well-preserved fossils (both brachiopods and conodonts) shows that the former are offset by -2.1(±0.4)‰. Diagenetic modeling suggests that these offsets were the product mainly of early diagenesis at burial temperatures of ~50-80°C and water/rock ratios of <10. Authigenic carbonates precipitated during early diagenesis represent a potentially major sink for isotopically light carbon at a global scale that has received relatively little attention to date.TJA thanks the Sedimentary Geology and Paleobiology program of the U.S. National Science Foundation (NSF EAR-1053449), the NASA Exobiology program (NNX13AJ1IG), and the China University of Geosciences—Wuhan (SKL-GPMR program GPMR201301, and SKL-BGEG programBGL21407) for their support. This study was funded by Deutsche Forschungsgemeinschaft (DFG; projects KO1829/12-1, KO1829/12-2 and KO2011/8-1)

Atomic Hydrogen and Star Formation in the Bridge/Ring Interacting Galaxy Pair NGC 7714/7715 (Arp 284)

We present high spatial resolution 21 cm HI maps of the interacting galaxy pair NGC 7714/7715. We detect a massive (2 x 10**9 M(sun)) HI bridge connecting the galaxies that is parallel to but offset from the stellar bridge. A chain of HII regions traces the gaseous bridge, with H-alpha peaks near but not on the HI maxima. An HI tidal tail is also detected to the east of the smaller galaxy NGC 7715, similarly offset from a stellar tail. The strong partial stellar ring on the eastern side of NGC 7714 has no HI counterpart, but on the opposite side of NGC 7714 there is a 10**9 M(sun) HI loop 11 kpc in radius. Within the NGC 7714 disk, clumpy HI gas is observed associated with star formation regions. Redshifted HI absorption is detected towards the starburst nucleus. We compare the observed morphology and gas kinematics with gas dynamical models in which a low-mass companion has an off-center prograde collision with the outer disk of a larger galaxy. These simulations suggest that the bridge in NGC 7714/7715 is a hybrid between bridges seen in systems like M51 and the purely gaseous `splash' bridges found in ring galaxies like the Cartwheel. The offset between the stars and gas in the bridge may be due to dissipative cloud-cloud collisions occuring during the impact of the two gaseous disks.Comment: 31 pages, Latex, 11 figures, to be published in the July 10, 1997 issue of the Astrophysical Journa

Proenkephalin and risk of developing chronic kidney disease:The Prevention of Renal and Vascular End-stage Disease study

BACKGROUND: Proenkephalin (pro-ENK) was recently found to be associated with low estimated glomerular filtration rate (eGFR). The association of pro-ENK with urinary albumin excretion (UAE), another marker for chronic kidney disease (CKD), has not been investigated. We examined the association of pro-ENK with eGFR and UAE as markers of CKD. METHODS: We included 4375 subjects of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study. CKDeGFR was defined as development of eGFR <60 ml/min/1.73 m2 and CKDUAE as albuminuria >30 mg/24 h. RESULTS: Baseline median pro-ENK was 52.2 (IQR: 44.9-60.5) pmol/L. After a median follow-up of 8.4 (IQR: 7.9-8.9) years, 183 subjects developed CKDeGFR and 371 developed CKDUAE. The association of pro-ENK with CKDeGFR was modified by sex (Pinteraction < 0.1), in such a way that after adjustment, the association only remained significant in men (adjusted hazard ratio per SD increase in 10log-transformed pro-ENK, 1.65; 95% CI: 1.15-2.36) and not in women (0.83; 0.58-1.20). No significant association was observed between pro-ENK and CKDUAE risk (0.83; 0.58-1.20). CONCLUSIONS: High pro-ENK is associated with increased risk of CKDeGFR in men, but not in women. No association of pro-ENK with CKDUAE was observed. These results should be interpreted with caution, since residual confounding and potential overfitting of models could have influenced the results

The effect of galaxy mass ratio on merger--driven starbursts

We employ numerical simulations of galaxy mergers to explore the effect of galaxy mass ratio on merger--driven starbursts. Our numerical simulations include radiative cooling of gas, star formation, and stellar feedback to follow the interaction and merger of four disk galaxies. The galaxy models span a factor of 23 in total mass and are designed to be representative of typical galaxies in the local Universe. We find that the merger--driven star formation is a strong function of merger mass ratio, with very little, if any, induced star formation for large mass ratio mergers. We define a burst efficiency that is useful to characterize the merger--driven star formation and test that it is insensitive to uncertainties in the feedback parameterization. In accord with previous work we find that the burst efficiency depends on the structure of the primary galaxy. In particular, the presence of a massive stellar bulge stabilizes the disk and suppresses merger--driven star formation for large mass ratio mergers. Direct, co--planar merging orbits produce the largest tidal disturbance and yield that most intense burst of star formation. Contrary to naive expectations, a more compact distribution of gas or an increased gas fraction both decrease the burst efficiency. Owing to the efficient feedback model and the newer version of SPH employed here, the burst efficiencies of the mergers presented here are smaller than in previous studies.Comment: 26 pages, 21 figures, submitted to MNRA