Michigan Technological University

About: Michigan Technological University is a education organization based out in Houghton, Michigan, United States. It is known for research contribution in the topics: Population & Volcano. The organization has 8023 authors who have published 17422 publications receiving 481780 citations. The organization is also known as: MTU & Michigan Tech.

The 2018 rift eruption and summit collapse of Kīlauea Volcano

Abstract: In 2018, Kīlauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu‘u ‘Ō‘ō vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 km. A 4 May earthquake (M6.9) produced ~5 m of fault slip. Lava erupted at rates exceeding 100 m 3 /s, eventually covering 35.5 km 2 . The summit magma system partially drained, producing minor explosions and near-daily collapses releasing energy equivalent to M4.7-M5.4 earthquakes. Activity declined rapidly on 4 August. Summit collapse and lava flow volume estimates are roughly equivalent—about 0.8 km 3 . Careful historical observation and monitoring of Kīlauea enabled successful forecasting of hazardous events.

Increasing Mechanical Strength of Gelatin Hydrogels by Divalent Metal Ion Removal

Abstract: The usage of gelatin hydrogel is limited due to its instability and poor mechanical properties, especially under physiological conditions Divalent metal ions present in gelatin such as Ca2+ and Fe2+ play important roles in the gelatin molecule interactions The objective of this study was to determine the impact of divalent ion removal on the stability and mechanical properties of gelatin gels with and without chemical crosslinking The gelatin solution was purified by Chelex resin to replace divalent metal ions with sodium ions The gel was then chemically crosslinked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) Results showed that the removal of divalent metal ions significantly impacted the formation of the gelatin network The purified gelatin hydrogels had less interactions between gelatin molecules and form larger-pore network which enabled EDC to penetrate and crosslink the gel more efficiently The crosslinked purified gels showed small swelling ratio, higher crosslinking density and dramatically increased storage and loss moduli The removal of divalent ions is a simple yet effective method that can significantly improve the stability and strength of gelatin hydrogels The in vitro cell culture demonstrated that the purified gelatin maintained its ability to support cell attachment and spreading

Auditor Tenure and the Ability to Meet or Beat Earnings Forecasts

Abstract: We examine the relation between auditor tenure and a firm's ability to use discretionary accruals to meet or beat analysts' earnings forecasts. Regulators have long expressed concern over the use of earnings management to attain earnings targets. These concerns are compounded by lingering questions over whether long-term auditor-client relationships impair an auditor's ability to independently stem such practices. The profession counter-argues that mandatory auditor rotation reduces auditors' familiarity with the client and adversely affects audit quality. Consistent with both arguments, we find that firms with both short (two to three years) and long (13-15 years or more) tenure are more likely to report levels of discretionary accruals that allow them to meet or beat earnings forecasts. The results suggest that while regulatory mandates for periodic auditor turnover have negative effects, sustained long term auditor-client relationships may be also detrimental to audit quality. The generalizability of our results may not extend to firms that are not covered by analysts, as these firms do not face the same public pressure to manage earnings in order to meet or beat expectations.

Determination of time- and height-resolved volcanic ash emissions and their use for quantitative ash dispersion modeling: the 2010 Eyjafjallajökull eruption

Abstract: . The April–May, 2010 volcanic eruptions of Eyjafjallajokull, Iceland caused significant economic and social disruption in Europe whilst state of the art measurements and ash dispersion forecasts were heavily criticized by the aviation industry. Here we demonstrate for the first time that large improvements can be made in quantitative predictions of the fate of volcanic ash emissions, by using an inversion scheme that couples a priori source information and the output of a Lagrangian dispersion model with satellite data to estimate the volcanic ash source strength as a function of altitude and time. From the inversion, we obtain a total fine ash emission of the eruption of 8.3 ± 4.2 Tg for particles in the size range of 2.8–28 μm diameter. We evaluate the results of our model results with a posteriori ash emissions using independent ground-based, airborne and space-borne measurements both in case studies and statistically. Subsequently, we estimate the area over Europe affected by volcanic ash above certain concentration thresholds relevant for the aviation industry. We find that during three episodes in April and May, volcanic ash concentrations at some altitude in the atmosphere exceeded the limits for the "Normal" flying zone in up to 14 % (6–16 %), 2 % (1–3 %) and 7 % (4–11 %), respectively, of the European area. For a limit of 2 mg m−3 only two episodes with fractions of 1.5 % (0.2–2.8 %) and 0.9 % (0.1–1.6 %) occurred, while the current "No-Fly" zone criterion of 4 mg m−3 was rarely exceeded. Our results have important ramifications for determining air space closures and for real-time quantitative estimations of ash concentrations. Furthermore, the general nature of our method yields better constraints on the distribution and fate of volcanic ash in the Earth system.

Evidence of NOx production within or upon ice particles in the Greenland snowpack

Abstract: NOx and NOy were determined in the interstitial air of surface snow and in ambient air at Summit, Greenland. NOx levels in interstitial air were 3 to >10 times those in ambient air, and were generally greater than ambient NOy levels. [NOy] in interstitial air varied diurnally in a manner consistent with photochemical generation within the snowpack. These observations imply that photochemical reactions occurring within or upon the ice crystals of surface snow produced NOx from a N-reservoir compound within the snow. Average [NOx]:[HNO3] and [NOx]:[NOy] ratios in ambient air above the snow were elevated relative to other remote sites, indicating that NOx release within the snowpack may have altered NOx levels in the overlying atmospheric boundary layer. We suggest that the observed release of NOx may have been initiated by photolysis of nitrate, present in relative abundance in surface snow at Summit. Such a process may affect levels of nitrate and other compounds in surface snow, the overlying atmosphere, and glacial ice, and its potential role in cirrus cloud chemistry should be investigated.