High-energy effective theory for matter on close Randall Sundrum branes

Extending the analysis of hep-th/0504128, we obtain a formal expression for the coupling between brane matter and the radion in a Randall-Sundrum braneworld. This effective theory is correct to all orders in derivatives of the radion in the limit of small brane separation, and, in particular, contains no higher than second derivatives. In the case of cosmological symmetry the theory can be obtained in closed form and reproduces the five-dimensional behaviour. Perturbations in the tensor and scalar sectors are then studied. When the branes are moving, the effective Newtonian constant on the brane is shown to depend both on the distance between the branes and on their velocity. In the small distance limit, we compute the exact dependence between the four-dimensional and the five-dimensional Newtonian constants.Comment: Updated version as published in PR

Two Alternating Motor Programs Drive Navigation in Drosophila Larva

When placed on a temperature gradient, a Drosophila larva navigates away from excessive cold or heat by regulating the size, frequency, and direction of reorientation maneuvers between successive periods of forward movement. Forward movement is driven by peristalsis waves that travel from tail to head. During each reorientation maneuver, the larva pauses and sweeps its head from side to side until it picks a new direction for forward movement. Here, we characterized the motor programs that underlie the initiation, execution, and completion of reorientation maneuvers by measuring body segment dynamics of freely moving larvae with fluorescent muscle fibers as they were exposed to temporal changes in temperature. We find that reorientation maneuvers are characterized by highly stereotyped spatiotemporal patterns of segment dynamics. Reorientation maneuvers are initiated with head sweeping movement driven by asymmetric contraction of a portion of anterior body segments. The larva attains a new direction for forward movement after head sweeping movement by using peristalsis waves that gradually push posterior body segments out of alignment with the tail (i.e., the previous direction of forward movement) into alignment with the head. Thus, reorientation maneuvers during thermotaxis are carried out by two alternating motor programs: (1) peristalsis for driving forward movement and (2) asymmetric contraction of anterior body segments for driving head sweeping movement

Heterogeneity in the effect of marked weight loss on metabolic function in women with obesity

BACKGROUNDThere is considerable heterogeneity in the effect of weight loss on metabolic function in people with obesity.METHODSWe evaluated muscle and liver insulin sensitivity, body composition, and circulating factors associated with insulin action before and after approximately 20% weight loss in women identified as Responders (n = 11) or Non-responders (n = 11), defined as the top (\u3e75% increase) and bottom (\u3c5% increase) quartiles of the weight loss-induced increase in glucose disposal rate (GDR) during a hyperinsulinemic-euglycemic clamp procedure, among 43 women with obesity (BMI: 44.1 ± 7.9 kg/m2).RESULTSAt baseline, GDR, which provides an index of muscle insulin sensitivity, and the hepatic insulin sensitivity index were more than 50% lower in Responders than Non-responders, but both increased much more after weight loss in Responders than Non-responders, which eliminated the differences between groups. Weight loss also caused greater decreases in intrahepatic triglyceride content and plasma adiponectin and PAI-1 concentrations in Responders than Non-responders and greater insulin-mediated suppression of plasma free fatty acids, branched-chain amino acids, and C3/C5 acylcarnitines in Non-responders than Responders, so that differences between groups at baseline were no longer present after weight loss. The effect of weight loss on total body fat mass, intra-abdominal adipose tissue volume, adipocyte size, and circulating inflammatory markers were not different between groups.CONCLUSIONThe results from our study demonstrate that the heterogeneity in the effects of marked weight loss on muscle and hepatic insulin sensitivity in people with obesity is determined by baseline insulin action, and reaches a ceiling when normal insulin action is achieved.TRIAL REGISTRATIONNCT00981500, NCT01299519, NCT02207777.FUNDINGNIH grants P30 DK056341, P30 DK020579, P30 DK052574, UL1 TR002345, and T32 HL13035, the American Diabetes Association (1-18-ICTS-119), the Longer Life Foundation (2019-011), and the Atkins Philanthropic Trust

The final stages of slip and volcanism on an oceanic detachment fault at 13°48′N, Mid‐Atlantic Ridge

Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 19 (2018): 3115-3127, doi:10.1029/2018GC007536.While processes associated with initiation and maintenance of oceanic detachment faults are becoming better constrained, much less is known about the tectonic and magmatic conditions that lead to fault abandonment. Here we present results from near‐bottom investigations using the submersible Alvin and autonomous underwater vehicle Sentry at a recently extinct detachment fault near 13°48′N, Mid‐Atlantic Ridge, that allow documentation of the final stages of fault activity and magmatism. Seafloor imagery, sampling, and near‐bottom magnetic data show that the detachment footwall is intersected by an ~850 m‐wide volcanic outcrop including pillow lavas. Saturation pressures in these vesicular basalts, based on dissolved H2O and CO2, are less than their collection pressures, which could be explained by eruption at a shallower level than their present depth. Sub‐bottom profiles reveal that sediment thickness, a loose proxy for seafloor age, is ~2 m greater on top of the volcanic terrain than on the footwall adjacent to the hanging‐wall cutoff. This difference could be explained by current‐driven erosion in the axial valley or by continued slip after volcanic emplacement, on either a newly formed or pre‐existing fault. Since current speeds near the footwall are unlikely to be sufficient to cause significant erosion, we favor the hypothesis that detachment slip continued after the episode of magmatism, consistent with growing evidence that oceanic detachments can continue to slip despite hosting magmatic intrusions.National Science Foundation (NSF) Grant Numbers: OCE‐1259218, OCE‐1260578, OCE‐17365472019-03-1

Atoh1 \u3csup\u3e+\u3c/sup\u3e secretory progenitors possess renewal capacity independent of Lgr5 \u3csup\u3e+\u3c/sup\u3e cells during colonic regeneration

During homeostasis, the colonic epithelium is replenished every 3–5 days by rapidly cycling Lgr5 + stem cells. However, various insults can lead to depletion of Lgr5 + stem cells, and colonic epithelium can be regenerated from Lgr5-negative cells. While studies in the small intestine have addressed the lineage identity of the Lgr5-negative regenerative cell population, in the colon this question has remained unanswered. Here, we set out to identify which cell(s) contribute to colonic regeneration by performing genetic fate-mapping studies of progenitor populations in mice. First, using keratin-19 (Krt19) to mark a heterogeneous population of cells, we found that Lgr5-negative cells can regenerate colonic crypts and give rise to Lgr5 + stem cells. Notch1 + absorptive progenitor cells did not contribute to epithelial repair after injury, whereas Atoh1 + secretory progenitors did contribute to this process. Additionally, while colonic Atoh1 + cells contributed minimally to other lineages during homeostasis, they displayed plasticity and contributed to epithelial repair during injury, independent of Lgr5 + cells. Our findings suggest that promotion of secretory progenitor plasticity could enable gut healing in colitis

Effects of diet versus gastric bypass on metabolic function in diabetes

BackgroundSome studies have suggested that in people with type 2 diabetes, Roux-en-Y gastric bypass has therapeutic effects on metabolic function that are independent of weight loss.MethodsWe evaluated metabolic regulators of glucose homeostasis before and after matched (approximately 18%) weight loss induced by gastric bypass (surgery group) or diet alone (diet group) in 22 patients with obesity and diabetes. The primary outcome was the change in hepatic insulin sensitivity, assessed by infusion of insulin at low rates (stages 1 and 2 of a 3-stage hyperinsulinemic euglycemic pancreatic clamp). Secondary outcomes were changes in muscle insulin sensitivity, beta-cell function, and 24-hour plasma glucose and insulin profiles.ResultsWeight loss was associated with increases in mean suppression of glucose production from baseline, by 7.04 μmol per kilogram of fat-free mass per minute (95% confidence interval [CI], 4.74 to 9.33) in the diet group and by 7.02 μmol per kilogram of fat-free mass per minute (95% CI, 3.21 to 10.84) in the surgery group during clamp stage 1, and by 5.39 (95% CI, 2.44 to 8.34) and 5.37 (95% CI, 2.41 to 8.33) μmol per kilogram of fat-free mass per minute in the two groups, respectively, during clamp stage 2; there were no significant differences between the groups. Weight loss was associated with increased insulin-stimulated glucose disposal, from 30.5±15.9 to 61.6±13.0 μmol per kilogram of fat-free mass per minute in the diet group and from 29.4±12.6 to 54.5±10.4 μmol per kilogram of fat-free mass per minute in the surgery group; there was no significant difference between the groups. Weight loss increased beta-cell function (insulin secretion relative to insulin sensitivity) by 1.83 units (95% CI, 1.22 to 2.44) in the diet group and by 1.11 units (95% CI, 0.08 to 2.15) in the surgery group, with no significant difference between the groups, and it decreased the areas under the curve for 24-hour plasma glucose and insulin levels in both groups, with no significant difference between the groups. No major complications occurred in either group.ConclusionsIn this study involving patients with obesity and type 2 diabetes, the metabolic benefits of gastric bypass surgery and diet were similar and were apparently related to weight loss itself, with no evident clinically important effects independent of weight loss. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT02207777.)

An open source, FPGA-based LeKID readout for BLAST-TNG: Pre-flight results

We present a highly frequency multiplexed readout for large-format superconducting detector arrays intended for use in the next generation of balloon-borne and space-based sub-millimeter and far-infrared missions. We will demonstrate this technology on the upcoming NASA Next Generation Balloon-borne Large Aperture Sub-millimeter Telescope (BLAST-TNG) to measure the polarized emission of Galactic dust at wavelengths of 250, 350 and 500 microns. The BLAST-TNG receiver incorporates the first arrays of Lumped Element Kinetic Inductance Detectors (LeKID) along with the first microwave multiplexing readout electronics to fly in a space-like environment and will significantly advance the TRL for these technologies. After the flight of BLAST-TNG, we will continue to improve the performance of the detectors and readout electronics for the next generation of balloon-borne instruments and for use in a future FIR Surveyor. Read More: http://www.worldscientific.com/doi/abs/10.1142/S225117171641003

Observation of off-diagonal geometric phase in polarized neutron interferometer experiments

Off-diagonal geometric phases acquired in the evolution of a spin-1/2 system have been investigated by means of a polarized neutron interferometer. Final counts with and without polarization analysis enable us to observe simultaneously the off-diagonal and diagonal geometric phases in two detectors. We have quantitatively measured the off-diagonal geometric phase for noncyclic evolutions, confirming the theoretical predictions. We discuss the significance of our experiment in terms of geometric phases (both diagonal and off-diagonal) and in terms of the quantum erasing phenomenon.Comment: pdf, 22 pages + 8 figures (included in the pdf). In print on Phys. Rev.