Bruce Allen Maxwell

Ecological Causes and Consequences of Demographic Change in the New West

R areas in the American West are undergoing a dra m a tic tra n s i ti on in dem ogra phy, econ om i c s ,a n d eco s ys tem s . Long known as the “Wi l d ” We s t , the regi on has been ch a racteri zed by low human pop u l a ti on den s i ties and vast tracts of u n s et t l ed or undevel oped land (Wi l k i n s on 1993, Power 1998). For most of the 1900s, the pop u l a ti on of m a ny ru ral areas in the West grew very slowly or even dec re a s ed . Because local econ omies were based on natu ral re s o u rce indu s tries su ch as mining, l oggi n g, f a rm i n g, and ra n ch i n g, m a ny re s i dents of the regi on con s i dered con s erva ti on stra tegies on public lands detri m ental to local econ omic devel opm en t . E f forts to establish natu re re s erves and to pre s erve p u blic lands from com m ercial devel opm ent were seen as res tri cting the use of vital natu ral re s o u rce s . In recent dec ade s ,p a rts of that Wild West have given way to the “ New ” West (Ri ebsame et al. 1 9 9 7 ) . People from t h ro u gh o ut the Un i ted States have been migra ting to the Rocky Mountains and the inland We s t . With a pop u l a ti on growth ra te of 2 5 . 4 % , the mountain West was the faste s t growing regi on of the co u n try du ring the 1990s. Su rpri si n gly, rapid pop u l a ti on increases are occ u rring not on ly in urban areas su ch as Denver and Salt Lake Ci ty but also in ru ra l co u n ti e s ,m a ny of wh i ch are gaining pop u l a ti on even faster than urban areas (Th eobald 2000). Some 67% of the co u nties in the Rocky Mountains grew faster than the nati onal avera ge du ring the 1990s (Beyers and Nel s on 2000). Con s equ en t ly, s m a ll cities su ch as Bozem a n , Mon t a n a , and Moa b, Ut a h , a re beginning to ex peri en ce traffic con ge s ti on and s prawl . Some of the ru ral pop u l a ti on growth in the New We s t repre s ents an intra regi onal red i s tri buti on of people from the h i gh plains, wh i ch con ti nue to lose pop u l a ti on (Jo h n s on 1 9 9 8 ) , to more mountainous are a s . Ma ny of the new re s i den t s , h owever, a re in-migrants from other regi ons thro u gh o ut the Un i ted States (Ri ebsame et al. 1 9 9 7 ) . The re s i dents of a ru ra l su b d ivi s i on in a boom co u n ty in Montana might inclu de recent arrivals from big East Coast citi e s ,m i dwe s tern farm s ,a n d the nearest small town . Am ong the in-migrants are reti ree s , we a l t hy young adu l t s , and profe s s i onals in com p uter techn o l ogy, real estate , and other servi ce indu s tries (Nel s on 1999).

Humans, Hydrology, and the Distribution of Inorganic Nutrient Loading to the Ocean

Abstract Most modern estimates of dissolved nitrogen and phosphorus delivery to the ocean use Meybecks estimates from approximately 30 large rivers. We have derived an extended database of approximately 165 sites with nutrient loads. For both dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP), the logarithmic yields (log [load/area]) can be parameterized as functions of log (population density) and log (runoff/area) (R2 for DIN and DIP approximately 0.6). Landscape production of DIN and DIP is largely assimilated. Even though DIN and DIP follow substantially different biogeochemical cycles, loading for DIN and DIP is tightly coupled (R2 for log DIN versus log DIP approximately 0.8), with a constant loading ratio of about 18:1. Estimates of DIN and DIP fluxes are distributed globally around the world coastlines by using basin population density and runoff at 0.5° increments of latitude and longitude. We estimate that total loads for the 1990s are about three times Meybecks estimates for the 1970s.

GRACE: an autonomous robot for the AAAI Robot challenge

In an attempt to solve as much of the AAAI Robot Challenge as possible, five research institutions representing academia, industry, and government integrated their research into a single robot named GRACE. This article describes this first-year effort by the GRACE team, including not only the various techniques each participant brought to GRACE but also the difficult integration effort itself.

Rivers, runoff, and reefs

Abstract The role of terrigenous sediment in controlling the occurrence of coral reef ecosystems is qualitatively understood and has been studied at local scales, but has not been systematically evaluated on a global-to-regional scale. Current concerns about degradation of reef environments and alteration of the hydrologic and sediment cycles place the issue at a focal point of multiple environmental concerns. We use a geospatial clustering of a coastal zone database of river and local runoff identified with 0.5° grid cells to identify areas of high potential runoff effects, and combine this with a database of reported coral reef locations. Coastal cells with high runoff values are much less likely to contain reefs than low runoff cells and GIS buffer analysis demonstrates that this inhibition extends to offshore ocean cells as well. This analysis does not uniquely define the effects of sediment, since salinity, nutrients, and contaminants are potentially confounding variables also associated with runoff. However, sediment effects are likely to be a major factor and a basis is provided for extending the study to higher resolution with more specific variables.

Integrating robotics research with undergraduate education

Swarthmore College takes a two-pronged approach to undergraduate education by integrating educational goals with robotics research. First, it offers courses in artificial intelligence, computer vision and robotics. Both AI and computer vision serve as prerequisites for the robotics course. Second, it involves students in ongoing research projects as part of their undergraduate experience. To keep up with the wide-ranging, fast-moving robotics field, education must be adaptive and multidisciplinary. The authors describe two undergraduate group projects they conducted, one from 1998 at the University of North Dakota advised by Maxwell, and one from 1999 at Swarthmore advised by both authors. The impetus for these projects was the American Association for Artificial Intelligences (AAAIs) annual robot competition. These experiences led to the development of a new robotics course at Swarthmore, which they co-taught in the spring of 2000.

Factors Associated With Concussion-like Symptom Reporting in High School Athletes

IMPORTANCE Every state in the United States has passed legislation for sport-related concussion, making this health issue important for physicians and other health care professionals. Safely returning athletes to sport after concussion relies on accurately determining when their symptoms resolve. OBJECTIVE To evaluate baseline concussion-like symptom reporting in uninjured adolescent student athletes. DESIGN, SETTING, AND PARTICIPANTS In this cross-sectional, observational study, we studied 31 958 high school athletes from Maine with no concussion in the past 6 months who completed a preseason baseline testing program between 2009 and 2013. RESULTS Symptom reporting was more common in girls than boys. Most students with preexisting conditions reported one or more symptoms (60%-82% of boys and 73%-97% of girls). Nineteen percent of boys and 28% of girls reported having a symptom burden resembling an International Classification of Diseases, 10th Revision (ICD-10) diagnosis of postconcussional syndrome (PCS). Students with preexisting conditions were even more likely to endorse a symptom burden that resembled PCS (21%-47% for boys and 33%-72% for girls). Prior treatment of a psychiatric condition was the strongest independent predictor for symptom reporting in boys, followed by a history of migraines. For girls, the strongest independent predictors were prior treatment of a psychiatric condition or substance abuse and attention-deficit/hyperactivity disorder. The weakest independent predictor of symptoms for both sexes was history of prior concussions. CONCLUSIONS AND RELEVANCE In the absence of a recent concussion, symptom reporting is related to sex and preexisting conditions. Consideration of sex and preexisting health conditions can help prevent misinterpretation of symptoms in student athletes who sustain a concussion.

A bi-illuminant dichromatic reflection model for understanding images

This paper presents a new model for understanding the appearance of objects that exhibit both body and surface reflection under realistic illumination. Specifically, the model represents the appearance of surfaces that interact with a dominant illuminant and a non-negligible ambient illuminant that may have different spectral power distributions. Real illumination environments usually have an ambient illuminant, and the current dynamic range of consumer cameras is sufficient to capture significant information in shadows. The bi-illuminant dichromatic reflection model explains numerous empirical findings in the literature and has implications for commonly used chromaticity spaces that claim to be illumination invariant but are not in many natural situations. One outcome of the model is the first 2-D chromaticity space for an RGB image that is robust to illumination change given dominant and ambient illuminants with different spectral power distributions.

The typological approach to submarine groundwater discharge (SGD).

Coastal zone managers need to factor submarine groundwater discharge (SGD) in their integration. SGD provides a pathway for the transfer of freshwater, and its dissolved chemical burden, from the land to the coastal ocean. SGD reduces salinities and provides nutrients to specialized coastal habitats. It also can be a pollutant source, often undetected, causing eutrophication and triggering nuisance algal blooms. Despite its importance, SGD remains somewhat of a mystery in most places because it is usually unseen and difficult to measure. SGD has been directly measured at only about a hundred sites worldwide. A typology generated by the Land–Ocean Interaction in the Coastal Zone (LOICZ) Project is one of the few tools globally available to coastal resource managers for identifying areas in their jurisdiction where SGD may be a confounding process. (LOICZ is a core project of the International Geosphere/Biosphere Programme.) Of the hundreds of globally distributed parameters in the LOICZ typology, a SGD subset of potentially relevant parameters may be culled. A quantitative combination of the relevant hydrological parameters can serve as a proxy for the SGD conditions not directly measured. Web-LOICZ View, geospatial software then provides an automated approach to clustering these data into groups of locations that have similar characteristics. It permits selection of variables, of the number of clusters desired, and of the clustering criteria, and provides means of testing predictive results against independent variables. Information on the occurrence of a variety of SGD indicators can then be incorporated into regional clustering analysis. With such tools, coastal managers can focus attention on the most likely sites of SGD in their jurisdiction and design the necessary measurement and modeling programs needed for integrated management.

Physics-Based Segmentation of Complex Objects Using Multiple Hypotheses of Image Formation

We present a general framework for the segmentation of complex scenes using multiple physical hypotheses of image formation. These hypotheses specify broad classes for the shape, illumination, and material properties of simple image regions. Through analysis, merging, and filtering of hypotheses the framework generates a ranked list of segmentations. We have implemented an algorithm based upon this framework and show example segmentations of scenes containing multicolored piece-wise uniform dielectric objects. By using this new approach we can intelligently segment scenes with objects of greater complexity than previous physics-based algorithms. The results show that by using general physical models we can obtain segmentations that correspond more closely to objects in a scene than segmentations found using only color.

Mobile robot localization with sparse landmarks

This paper describes a mobile robot system designed to explore and map an indoor area such as is encountered in urban search and rescue mock-ups. The robot uses homogeneous artificial landmarks deployed during exploration for localization as it constructs a map, determining landmark distance and bearing with groundplane calculations from a single camera and using Kalman filtering techniques to perform localization. When implemented on a Magellan II mobile robot, the localization technique correctly localized the robot while exploring and mapping.