Precambrian non-marine stromatolites in alluvial fan deposits, the Copper Harbor Conglomerate, upper Michigan

Laminated cryptalgal carbonates occur in the Precambrian Copper Harbor Conglomerate of northern Michigan, which was deposited in the Keweenawan Trough, an aborted proto-oceanic rift. This unit is composed of three major facies deposited by braided streams on a large alluvial-fan complex. Coarse clastics were deposited in braided channels, predominantly as longitudinal bars, whereas cross-bedded sandstones were deposited by migrating dunes or linguoid bars. Fine-grained overbank deposits accumulated in abandoned channels. Gypsum moulds and carbonate-filled cracks suggest an arid climate during deposition. Stromatolites interstratified with these clastic facies occur as laterally linked drapes over cobbles, as laterally linked contorted beds in mudstone, as oncolites, and as poorly developed mats in coarse sandstones. Stromatolites also are interbedded with oolitic beds and intraclastic conglomerates. Stromatolitic microstructure consists of alternating detrital and carbonate laminae, and open-space structures. Radial-fibrous calcite fans are superimposed on the laminae. The laminae are interpreted as algal in origin, whereas the origin of the radial fibrous calcite is problematic. The stromatolites are inferred to have grown in lakes which occupied abandoned channels on the fan surface. Standing water on a permeable alluvial fan in an arid climate requires a high water table maintained by high precipitation, or local elevation of the water table, possibly due to the close proximity of a lake. Occurrence of stromatolites in the upper part of the Copper Harbor Conglomerate near the base of the lacustrine Nonesuch Shale suggests that these depositional sites may have been near the Nonesuch Lake.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72022/1/j.1365-3091.1983.tb00713.x.pd

γ -soft Ba 146 and the role of nonaxial shapes at N≈90

Low-spin states in the neutron-rich, N=90 nuclide Ba146 were populated following β decay of Cs146, with the goal of clarifying the development of deformation in barium isotopes through delineation of their nonyrast structures. Fission fragments of Cs146 were extracted from a 1.7-Ci Cf252 source and mass selected using the CAlifornium Rare Ion Breeder Upgrade (CARIBU) facility. Low-energy ions were deposited at the center of a box of thin β detectors, surrounded by a highly efficient high-purity Ge array. The new Ba146 decay scheme now contains 31 excited levels extending up to ∼2.5 MeV excitation energy, double what was previously known. These data are compared to predictions from the interacting boson approximation (IBA) model. It appears that the abrupt shape change found at N=90 in Sm and Gd is much more gradual in Ba and Ce, due to an enhanced role of the γ degree of freedom

Effect of flow rate, humidifier dome and water volume on maximising heated, humidified gas use for neonatal resuscitation

Aim: Dry, cold gas is used for neonatal resuscitation, contributing to low admission temperatures and exacerbation of lung injury. Recently, a method of heating and humidifying neonatal resuscitation gases has become available. We aimed to determine the optimal flow rate, humidifier chamber and water volume needed to reach 36. °C, and near 100% humidity at the patient T-piece in the shortest possible time. Method: A T-piece resuscitator was connected via a heated patient circuit to a humidifier chamber. Trials were performed using different gas flow rates (6, 8 and 10. L/min), humidification chambers (MR290, MR225) and water volumes (30. g, 108. g). Temperature was recorded at the humidifier chamber (T1), distal temperature probe (T2) and the T-piece (T3) over a 20. min period at 30. s intervals. A test lung was added during one trial. Results: No significant difference existed between flow rates 8. L/min and 10. L/min (p= 0.091, p= 0.631). T3 reached 36. °C and remained stable at 360. s (8. L/min, MR225, 30. mL); near 100% RH was reached at 107. s (10. L/min, MR225, 30. mL). T3 and humidity reached and remained stable at 480. s (10. L/min, MR290, 30. mL). Target temperature and humidity was not reached with the test lung. Conclusions: It is possible to deliver heated, humidified gases in neonatal resuscitation in a clinically acceptable timeframe. We suggest the set-up to achieve optimal temperature and humidity for resuscitation purposes is 10. L/min of gas flow, a MR290 humidification chamber, and 30. mL of water

Role of Lung-marginated Monocytes in an In Vivo Mouse Model of Ventilator-induced Lung Injury

Rationale: Recruited leukocytes play an important role in ventilator-induced lung injury, although studies have focused predominantly on neutrophils. Inflammatory subset Gr-1(high) monocytes are recruited to sites of inflammation and have been implicated in acute lung injury induced by systemic endotoxin. Objectives: To investigate the recruitment and role of Gr-1(high) monocytes in an in vivo mouse model of ventilator-induced lung injury. Methods: Anesthetized mice were ventilated with low or high stretch. Flow cytometry was used to quantify monocyte subset margination to the lungs, and to assess their in situ cellular activation in response to mechanical stretch. To investigate monocyte involvement in lung injury progression, a two-hit model was used, with a subclinical dose of lipopolysaccharide (intraperitoneal) given 2 hours prior to high-stretch ventilation. In some animals, monocytes were depleted using intravenous clodronate liposomes. Development of lung injury was assessed in ventilated animals by peak inspiratory pressure and respiratory system mechanics. Measurements and Main Results: High-stretch ventilation induced significant pulmonary margination of Gr-1(high) but not Gr-1(low) monocytes compared with nonventilated mice. These monocytes displayed increased activation status, with higher CD11b (vs. nonventilated mice) and lower L-selectin expression (vs. low-stretch ventilation). Lipopolysaccharide challenge led to enhanced lung margination of Gr-1(high) monocytes and neutrophils, and sensitized the lungs to high stretch-induced pulmonary edema. Clodronate-liposome pretreatment depleted lung monocytes (but not neutrophils) and significantly attenuated lung injury. Conclusions: High-stretch mechanical ventilation promotes pulmonary margination of activated Gr-1(high) monocytes, which play a role in the progression of ventilator-induced lung injur