313 research outputs found
Alaskan resources, current development. Traditional cultural values, and the role of LANDSAT data in current and future land use management planning
Past, present, and proposed applications of LANDSAT data for renewable resource assessments in Alaska are described. Specific projects briefly discussed include: a feasibility investigation applying LANDSAT data to caribou habitat mapping in northeast Alaska, analysis of a native corporate region in southwest Alaska, analysis of a game management unit in interior Alaska, and two proposed analyses in northwest Alaska. These analyses principally address range evaluations concerning caribou, moose, and Dall sheep, but results have application to other renewable resource themes. Application of resource assessment results to a statewide land use management plan is discussed
Application of ERTS imagery to the study of caribou movements and winter habitat
There are no author-identified significant results in this report
Use of LANDSAT imagery for wildlife habitat mapping in northeast and east central Alaska
There are no author-identified significant results in this report
A Survey of Lentic Waters with Respect to Dissolved and Particulate Lead
Some of the strongest temperature inversions in the world occur at
Fairbanks, Alaska. Benson (1970) has reported that a temperature gradient
of 10 to 30C/1OO m is common in the winter inversions that form at
Fairbanks. Air pollution is especially severe during these inversions
when it is accompanied by the formation of ice crystals in the air, a
condition known as ice fog. This phenomenon occurs when the temperature
drops below -20F (-35C) (Benson, 1970), and it intensifies with time if
the inversion is not broken.
The ice crystals in this fog have been found to adsorb dust and gasses,
including the lead halides which are present in the air as a result of the
combustion of tetraethyl lead and/or other lead-hydrocarbon compounds used
as anti-knock additives in automotive gasoline. Lazrus et al. (1970) have
found lead concentrations in precipitation to be highly significantly correlated
with the amount of gasoline used in the area sampled.
There are two factors that bring the concentration of lead to high
levels in ice fogs. Evaporation of the ice crystals tends to concentrate
pollutants in the air mass, especially over the core area of the city
where precipitation is retarded by the heating effect of the city. Also,
during the extreme cold weather accompanying this phenomenon, many people
allow their cars to idle when they are parked to increase performance and
for reasons of personal comfort.
Eventually, much of the pollutants suspended in the ice fog is precipitated and causes unnaturally high levels of lead in the snow. (Winchester et al., 1967). It is suspected that some of this particulate
lead collected in the snow may be carried along with the associated surface
runoff into 1entic (standing) surface waters during thawing. The
objectives of this project were:
1. to measure the amount of dissolved and particulate lead in a
number of selected 1entic waters in the Fairbanks area, and
2. to measure the amount of lead that has been incorporated into net plankton organisms located in the selected lentic waters.The work upon which this report is based was supported by funds (Project A-035-ALAS) provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the
Water Resources Act of 1964, as amended
Nutrient chemistry of a large, deep lake in subarctic Alaska
Project Officer
Eldor W. Schallock
Assessment and Criteria Development Division
Corvallis Environmental Research Laboratory
Corvallis, Oregon 97330;Corvallis Environmental Research Laboratory
Office of Research and Development
U. S. Environmental Protection Agency
Corvallis, Oregon 97330; R800276The primary objective of this project was to assess the state of the
water quality of Harding Lake, and to attempt to predict the effects of
future development within its watershed. Since the major effect of degradation
of water quality due to human activity is the promotion of nuisance
growths of plants, the major emphasis was placed on measurements of plant
growth and concentrations of the major nutrients they require. Planktonic
algal growth was found to be low, below 95.6 gm/m2/year, and the growth of
submerged rooted plants was found to be relatively less important at approximately
1.35 gm/m2/year. Measurements of the growth of attached algae were
not conducted, therefore the relative importance of their growth is currently
unknown.
A model for predicting the effect of future real estate development in
the watershed was modified and applied to this lake. This model adequately
describes current water quality conditions, and is assumed to have some
predictive ability, but several cautions concerning application of this
model to Harding Lake are discussed.
A secondary objective was to study the thermal regime of a deep subarctic
lake. Intensive water temperature measurements were made throughout
one year and less intensive measurements were conducted during two additional
years. The possibility that this lake may occasionally stratify thermally
under the ice and not mix completely in the spring was discovered. The
implications of this possibility are discussed for management of subarctic
lakes. Hydrologic and energy budgets of this lake are attempted; the annual
heat budget is estimated at 1.96 x 104 ± 1.7 x 103 cal/cm2.
The results of a study of domestic water supply and waste disposal
alternatives in the watershed, and the potential for enteric bacterial contamination
of the lake water are presented. Limited work on the zooplankton,
fishes, and benthic macroinvertebrates of this lake is also presented
Use of LANDSAT imagery for wildlife habitat mapping in northeast and eastcentral Alaska
There are no author-identified significant results in this report
Radiosurgery for brainstem metastases with and without whole brain radiotherapy: clinical series and literature review
Objective The objective of this study was to investigate outcomes for patients with brainstem metastases treated with stereotactic radiosurgery (SRS). Methods Patients with brainstem metastases treated with SRS between April 2006 and June 2012 were identified from a prospective database. Patient and treatment-related factors were recorded. Kaplan-Meier analysis was used to calculate survival and freedom from local and distant brain progression. Univariate and multivariate Cox regression was used to identify factors important for overall survival. Results In total, 44 patients received SRS for 48 brainstem metastases of whom 33 (75 %) also received whole brain radiotherapy (WBRT): 23 patients (52 %) WBRT prior to SRS, 6 (13.6 %) WBRT concurrently with SRS and 4 (9.0 %) WBRT after SRS. Eight patients received a second course ofWBRTat further progression. Median target volume was 1.33 cc (range 0.04–12.17) and median prescribed marginal dose was 15 Gy (range 10–22). There were four cases of local failure, and 6-month and 1-year freedom from local failure was 84.6 and 76.9 %, respectively. Median overall survival (OS) was 5.4 months. There were four cases of radionecrosis, 2 (4.8 %) of which were symptomatic. The absence of external beam brain radiotherapy (predominantly WBRT) showed a trend towards improved OS on univariate analysis. Neither local nor distant brain failure significantly impacted OS. Conclusion This retrospective series of patients treated with SRS for brainstem metastases, largely in combination with at least one course of WBRT, demonstrates that this approach is safe and results in good local control. In this cohort, no variables significantly impacted OS, including intracranial control
- …