A Post-Cold War Geography of Forced Migration in Kenya and Somalia

Drawing on recent research in the Horn of Africa, emerging patterns of managing forced migration in the post-Cold War landscape are identified and analyzed. While camps continue to house refugees, the meaning and value of ‘refugee’ have changed dramatically since the Cold War. Efforts to prevent people from crossing political borders to seek safety are increasing, giving rise to a new set of safe spaces. These new spaces are expressions of a distinct geopolitical discourse and take the names ‘UN protectedarea’, ‘preventive zone’, and ‘safe haven’. Their significance as a challenge to state-centric geopolitics both within conflict zones and as refugee camps is explored in the Kenya-Somalia context.     

Explicitly incorporating spatial dependence in predictive vegetation models in the form of explanatory variables: a Mojave Desert case study

Predictive vegetation modeling is defined as predicting the distribution of vegetation across a landscape based upon its relationship with environmental factors. These models generally ignore or attempt to remove spatial dependence in the data. When explicitly included in the model, spatial dependence can increase model accuracy. We develop presence/absence models for 11 vegetation alliances in the Mojave Desert with classification trees and generalized linear models, and use geostatistical interpolation to calculate spatial dependence terms used in the models. Results were mixed across models and methods, but in general, the spatial dependence terms more consistently increased model accuracy for widespread alliances. GLMs had higher accuracy in general.     

Green infrastructure,green space,and sustainable urbanism: geography’s important role

ABSTRACT

This paper is a broad review of green infrastructure theory and practice relative to urban sustainability and the space for geographers in these discussions. We use examples from various urban sustainability plans to highlight ways in which green infrastructure is being conceptualized and implemented. We explore how geography contributes research on green infrastructure as well as the emerging practices as seen within sustainability plans. We identify four areas in which geographers can influence both green infrastructure theory and practice: 1) scale; 2) mapping distribution; 3) sensitivity to place and locale; and 4) equity and access. We conclude that in these areas geographers have tremendous opportunity contribute more deliberately to sustainable urbanism.     

Characterization of marine debris in North Carolina salt marshes

Marine debris composition, density, abundance, and accumulation were evaluated in salt marshes in Carteret County, North Carolina seasonally between 2007 and 2009. We assessed relationships between human use patterns and debris type. Wave effects on marine debris density were examined using a GIS-based forecasting tool. We assessed the influence of site wave exposure, period, and height on debris quantity. Presence and abundance of debris were related to wave exposure, vegetation type and proximity of the strata to human population and human use patterns. Plastic pieces accounted for the majority of all debris. Small debris (0–5 cm) was primarily composed of foam pieces and was frequently affiliated with natural wrack. Large debris (>100 cm) was encountered in all marsh habitat types surveyed and was primarily composed of anthropogenic wood and derelict fishing gear. Marsh cleanup efforts should be targeted to specific habitat types or debris types to minimize further damage to sensitive habitats.     

Research Associates and the Production of Knowledge in the Field

This article introduces an important, but overlooked, actor—the research associate—into methodological discussions about the production of knowledge. We use the term research associate (rather than assistant) to encompass the individuals on whom researchers rely while conducting fieldwork. We seek to avoid the unidirectional hierarchy and power dynamics between researchers and associates, which place the researcher as expert and knowledge producer while obscuring the diversity of roles conducted by field associates. Therefore, throughout this article we examine and destabilize power dynamics and hierarchies and widen the range of what is considered research assistance in the coproduction of knowledge. We also highlight the ways in which geopolitics are written into encounters with ourselves and research associates, encounters that render and reveal the complexities of vulnerability and bodily risk in fieldwork. The goals of this article are threefold: to (1) introduce the influential role of research associates during the production and dissemination of knowledge, (2) situate the work of research associates in both fieldwork and methodological literature, and (3) problematize the invisibility of research associates in academic publications and discuss possible alternatives to how authorship is credited.     

Daily and Periodic Mobility Patterns of the Urban Homeless*

The intraurban mobility patterns of a sample of homeless individuals in the Skid Row area of Los Angeles is examined. Findings indicate that the voluntary mobility of homeless persons in the sample is related less to individual characteristics than to the availability and location of resources, particularly social supports.     

Joint estimation of GPS/BDS real-time clocks and initial results

We present the joint estimation model for Global Positioning System/BeiDou Navigation Satellite System (GPS/BDS) real-time clocks and present the initial satellite clock solutions determined from 106 stations of the international GNSS service multi-GNSS experiment and the BeiDou experimental tracking stations networks for 1 month in December, 2012. The model is shown to be efficient enough to have no practical computational limit for producing 1-Hz clock updates for real-time applications. The estimated clocks were assessed through the comparison with final clock products and the analysis of post-fit residuals. Using the estimated clocks and corresponding orbit products (GPS ultra-rapid-predicted and BDS final orbits), the root-mean-square (RMS) values of coordinate differences from ground truth values are around 1 and 2–3 cm for GPS-only and BDS-only daily mean static precise point positioning (PPP) solutions, respectively. Accuracy of GPS/BDS combined static PPP solutions falls in between that of GPS-only and BDS-only PPP results, with RMS values approximately 1–2 cm in all three components. For static sites, processed in the kinematic PPP mode, the daily RMS values are normally within 4 and 6 cm after convergence for GPS-only and BDS-only results, respectively. In contrast, the combined GPS/BDS kinematic PPP solutions show higher accuracy and shorter convergence time. Additionally, the BDS-only kinematic PPP solutions using clock products derived from the proposed joint estimation model were superior compared to those computed using the single-system estimation model.     

Differences in the Soluble,Residual Phosphate Concentrations at Which Coastal Phytoplankton Species Up-regulate Alkaline-Phosphatase Expression,as Measured By Flow-Cytometric Detection of ELF-97® Fluorescence

The enzyme-labeled fluorescence (ELF-97®) substrate produces an insoluble, fluorescent yellow-green product at the site of alkaline-phosphatase (AP) activity. Fifteen coastal phytoplankton species were tested to determine if AP activity could be detected in phosphate-depleted media. All species tested, except Synechococcus bacillaris, expressed AP activity. Subsequently, threshold concentrations of soluble reactive phosphate (SRP) at which AP activity could be detected by ELF-97® were determined for Chaetoceros neogracile, Chlorella autotrophica, Isochrysis sp., Prorocentrum minimum, and Tetraselmis chui. Microalgal species differed significantly in the SRP concentration at which AP activity was first detectable (10.1–16.4 µM), well above concentrations normally considered limiting for phytoplankton. P. minimum began to express AP activity at a higher SRP concentration than the other algal species; this may be attributable to a relatively high DNA/cell ratio in P. minimum, compared to the other phytoplankton. Thus, phytoplankton species may respond to phosphorus deficiency at high SRP concentrations.     

Catchment-scale observations at the Niwot Ridge long-term ecological research site

The Niwot Ridge and Green Lakes Valley (NWT) long-term ecological research (LTER) site collects environmental observations spanning both alpine and subalpine regimes. The first observations began in 1952 and have since expanded to nearly 300 available datasets over an area of 99 km² within the north-central Colorado Rocky Mountains that include hydrological (n = 101), biological (n = 79), biogeochemical (n = 62), and geographical (n = 56) observations. The NWT LTER database is well suited to support hydrologic investigations that require long-term and interdisciplinary data sets. Experimentation and data collection at the NWT LTER are designed to characterize ecological responses of high-mountain environments to changes in climate, nutrients, and water availability. In addition to the continuation of the many legacy NWT datasets, expansion of the breadth and utility of the NWT LTER database is driven by new initiatives including (a) a catchment-scale sensor network of soil moisture, temperature, humidity, and snow-depth observations to understand hydrologic connectivity and (b) snow-albedo alteration experiments using black sand to evaluate the effects of snow-disappearance on ecosystems. Together, these observational and experimental datasets provide a substantial foundation for hydrologic studies seeking to understand and predict changes to catchment and local-scale process interactions.