A comparison of presettlement and modern forest composition along an elevation gradient in central New Hampshire

Tree species composition is influenced not only by edaphic and climatic factors but also by natural and human-caused disturbances. To understand interactions among these influences, we compared forest species composition data from the time of European settlement with modern data. We derived elevation data for 2529 trees mapped by early land surveys (1770–1850) across a 1000 m elevation gradient in central New Hampshire and compared these with modern data (2004–2009) from the Forest Inventory and Analysis program (123 plots containing 2126 trees) and from permanent plots representing case studies of different land-use histories. Spruce and beech are much less abundant today at all elevations than they were prior to settlement, while maples and birches have increased. Fir, hemlock, pines, and oaks have changed little in distribution, although pines and oaks increased in abundance somewhat. Land-use history (agriculture below 500 m and cutting of various intensities at all elevations) is likely the primary explanation for these shifts, although climate change is also an important factor for some. A clearer understanding of presettlement forest composition improves our ability to separate the relative importance of natural and human-driven influences on the species composition of today’s forests

UPDATING AN EXPERT ELICITATION IN THE LIGHT OF NEW DATA: TEN YEARS OF PROBABILISTIC VOLCANIC HAZARD ANALYSIS FOR THE PROPOSED HIGH-LEVEL RADIOACTIVE WASTE REPOSITORY AT YUCCA MOUNTAIN, NEVADA

The U.S. Department of Energy (DOE) considers volcanism to be a potentially disruptive class of events that could affect the safety of the proposed high-level waste repository at Yucca Mountain. Volcanic hazard assessment in monogenetic volcanic fields depends on an adequate understanding of the temporal and spatial pattern of past eruptions. At Yucca Mountain, the hazard is due to an 11 Ma-history of basaltic volcanism with the latest eruptions occurring in three Pleistocene episodes to the west and south of Yucca Mountain. An expert elicitation convened in 1995-1996 by the DOE estimated the mean hazard of volcanic disruption of the repository as slightly greater than 10{sup -8} dike intersections per year with an uncertainty of about two orders of magnitude. Several boreholes in the region have encountered buried basalt in alluvial-filled basins; the youngest of these basalts is dated at 3.8 Ma. The possibility of additional buried basalt centers is indicated by a previous regional aeromagnetic survey conducted by the USGS that detected approximately 20 magnetic anomalies that could represent buried basalt volcanoes. Sensitivity studies indicate that the postulated presence of buried post-Miocene volcanoes to the east of Yucca Mountain could increase the hazard by an order of magnitude, and potentially significantly impact the results of the earlier expert elicitation. Our interpretation of the aeromagnetic data indicates that post-Miocene basalts are not present east of Yucca Mountain, but that magnetic anomalies instead represent faulted and buried Miocene basalt that correlates with nearby surface exposures. This interpretation is being tested by drilling. The possibility of uncharacterized buried volcanoes that could significantly change hazard estimates led DOE to support an update of the expert elicitation in 2004-2006. In support of the expert elicitation data needs, the DOE is sponsoring (1) a new higher-resolution, helicopter-borne aeromagnetic survey, completed in mid-2004, and (2) drilling of selected anomalies based on the aeromagnetic survey results to better characterize the number, location and age of buried volcanoes, which began in mid-2005. The new aeromagnetic survey detected the presence of 33 anomalies interpreted as possible buried volcanoes or faulted tuff bedrock. A program to drill ten of the anomalies has begun, with the selection of drill holes prioritized based on their potential impact on the hazard assessment

The use of propagation path corrections to improve regional seismic event location in western China

In an effort to improve the ability to locate seismic events in western China using only regional data, the authors have developed empirical propagation path corrections (PPCs) and applied such corrections using both traditional location routines as well as a nonlinear grid search method. Thus far, the authors have concentrated on corrections to observed P arrival times for shallow events using travel-time observations available from the USGS EDRs, the ISC catalogs, their own travel-tim picks from regional data, and data from other catalogs. They relocate events with the algorithm of Bratt and Bache (1988) from a region encompassing China. For individual stations having sufficient data, they produce a map of the regional travel-time residuals from all well-located teleseismic events. From these maps, interpolated PPC surfaces have been constructed using both surface fitting under tension and modified Bayesian kriging. The latter method offers the advantage of providing well-behaved interpolants, but requires that the authors have adequate error estimates associated with the travel-time residuals. To improve error estimates for kriging and event location, they separate measurement error from modeling error. The modeling error is defined as the travel-time variance of a particular model as a function of distance, while the measurement error is defined as the picking error associated with each phase. They estimate measurement errors for arrivals from the EDRs based on roundoff or truncation, and use signal-to-noise for the travel-time picks from the waveform data set

Retained Subintimal Pellet in a Carotid Artery

A shotgun pellet is depicted in the present image in a carotid artery under the intima, which remained intact without local complications for up to six months. There is lack of data regarding the natural history of such a carotid pellet, but the experience from the myocardium is that, in the absence of infection, completely embedded missiles are usually asymptomatic, tolerated well and may be left in place

Estimating Historical Forest Density From Land‐Survey Data: A Response to Baker and Williams (2018)

In the Western United States, historical forest conditions are used to inform land management and ecosystem restoration goals (North et al. 2009, Stephens et al. 2016). This interest is based on the premise that historical forests were resilient to ecological disturbances (Keane et al. 2018). Researchers throughout the United States have used the General Land Office (GLO) surveys of the late 19th and early 20th centuries to estimate historical forest conditions (Bourdo 1956, Schulte and Mladenoff 2001, Cogbill et al. 2002, Paciorek et al. 2016). These surveys were conducted throughout the United States and represent a systematic, historical sample of trees across a broad geographic area. A challenge of using GLO survey data is the accurate estimation of tree density from sparse witness tree data. Levine et al. (2017) tested the accuracy and precision of four plotless density estimators that can be applied to GLO survey sample data, including the Cottam (Cottam and Curtis 1956), Pollard (Pollard 1971), Morisita (Morisita 1957), and mean harmonic Voronoi density (MHVD; Williams and Baker 2011) estimators. The Cottam, Pollard, and Morisita are count‐based plotless density estimators (PDE) and have a history of being applied to GLO data (e.g., Kronenfeld and Wang 2007, Rhemtulla et al. 2009, Hanberry et al. 2012, Maxwell et al. 2014, Goring et al. 2016). The MHVD estimator is an area‐based PDE that has been applied by the study\u27s authors to sites in the western United States (Baker 2012, 2014), but had not been independently evaluated. Levine et al. (2017) found that the Morisita estimator was the least biased and most precise estimator for estimating density from GLO survey data, with a relative root mean square error ranging from 0.11 to 0.78 for the six study sites. Levine et al. (2017) also demonstrated the MHVD approach consistently overestimated density from 16% to 258% in all six study areas that were analyzed

Peritonitis secondary to traumatic duodenal laceration in the presence of a large pancreatic pseudocyst: a case report

<p>Abstract</p> <p>Introduction</p> <p>A pancreatic pseudocyst is a common sequela of severe acute pancreatitis. Commonly, it presents with abdominal pain and a mass in the epigastrium several weeks after the acute episode and can be managed conservatively, endoscopically or surgically. We report a patient with a pancreatic pseudocyst awaiting endoscopic therapy who developed a life-threatening complication following a rather innocuous trauma to the abdomen.</p> <p>Case presentation</p> <p>A 23-year-old Asian male student presented as an emergency with an acute abdomen a week after a minor trauma to his upper abdomen. The injury occurred when he was innocently punched in the abdomen by a friend. He experienced only moderate discomfort briefly at the time. His past medical history included coeliac disease and an admission four months previously with severe acute pancreatitis. He was hospitalized for 15 days; his pancreatitis was thought to be due to alcohol binge drinking on weekends. Ultrasound scanning showed no evidence of gallstone disease. Five days after the trauma, he became anorexic, lethargic and feverish and started vomiting bilious content. Seven days post-trauma, he presented to our emergency department with severe abdominal pain. An emergency laparotomy was performed where a transverse linear duodenal laceration was found at the junction of the first and second part of his duodenum, with generalized peritonitis. His stomach and duodenum were stretched over a large pancreatic pseudocyst posterior to his stomach. It was postulated that an incomplete duodenal injury (possibly a serosal tear) occurred following the initial minor trauma, which was followed by local tissue necrosis at the injury site resulting in a delayed presentation of generalized peritonitis.</p> <p>Conclusion</p> <p>This is the first reported case of a traumatic duodenal laceration following minor blunt trauma in the presence of a large pancreatic pseudocyst. Minor blunt abdominal trauma in a normal healthy adult would not be expected to result in a significant duodenal injury. In the presence of a large pseudocyst, however, the stretching of the duodenum over the pseudocyst had probably predisposed the duodenum to this injury. Patients awaiting therapeutic interventions for their pancreatic pseudocysts should be warned about this unusual but life-threatening risk following minor blunt abdominal trauma.</p

SMALL-VOLUME BASALTIC VOLCANOES: ERUPTIVE PRODUCTS AND PROCESSES, AND POST-ERUPTIVE GEOMORPHIC EVOLUTION IN CRATER FLAT (PLEISTOCENE), SOUTHERN NEVADA

Five Pleistocene basaltic volcanoes in Crater Flat (southern Nevada) demonstrate the complexity of eruption processes associated with small-volume basalts and the effects of initial emplacement characteristics on post-eruptive geomorphic evolution of the volcanic surfaces. The volcanoes record eruptive processes in their pyroclastic facies ranging from ''classical'' Strombolian mechanisms to, potentially, violent Strombolian mechanisms. Cone growth was accompanied, and sometimes disrupted, by effusion of lavas from the bases of cones. Pyroclastic cones were built upon a gently southward-sloping surface and were prone to failure of their down-slope (southern) flanks. Early lavas flowed primarily southward and, at Red and Black Cone volcanoes, carried abundant rafts of cone material on the tops of the flows. These resulting early lava fields eventually built platforms such that later flows erupted from the eastern (at Red Cone) and northern (at Black Cone) bases of the cones. Three major surface features--scoria cones, lava fields with abundant rafts of pyroclastic material, and lava fields with little or no pyroclastic material--experienced different post-eruptive surficial processes. Contrary to previous interpretations, we argue that the Pleistocene Crater Flat volcanoes are monogenetic, each having formed in a single eruptive episode lasting months to a few years, and with all eruptive products having emanated from the area of the volcanoes main cones rather than from scattered vents. Geochemical variations within the volcanoes must be interpreted within a monogenetic framework, which implies preservation of magma source heterogeneities through ascent and eruption of the magmas

Detection of underground structures and tunnels

This is the final report of a one year, Laboratory Directed Research and Development project at Los Alamos National Laboratory. There is a continuing need in the United States defense and drug interdiction for effective over, convert, and standoff means of detecting underground tunnels, structures, and objects. This project sought to begin an assessment of electromagnetic and gravitational gradient detection approaches to the detection of underground structures and tunnels