1,614 research outputs found
Soil morphology, soil water, and forest tree growth on three Cumberland Plateau landtypes
Relationships among soil morphology, soil water, and forest tree growth were investigated on three forested Cumberland Plateau landtypes at two locations, and a forest land classification system was evaluated. Two soil pits on each plot were opened for morphological descriptions, characterization, and moisture cell installation. Moisture cells were read for two years. Thirty-two soil properties from three genetic soil horizons at 132 points located with a 10 meter grid were used in multivariate statistical analyses. Dominant soils were Typic Fragiudults on uplands; Humic Hapludults and Typic Fragiumbrepts on slopes; and Aquic Dystrochrepts and Typic Haplaquepts on first-order bottoms. Parent materials were Pleistocene loess over shale and sandstone residuum. Clay mineralogy of the upper sequum was relatively young. Chlorite was common in A horizons, but only acid upland soils contained hydroxy-interlayered vermiculite. Kaolinite and quartz dominated residual soils. Gibbsite was in the most leached soil horizons and within buried paleosols. Cation exchange capacities averaged 15 cmol(p+)kg-1 on uplands and bottoms and 20 cmol(p+)kg-1 on slopes. Base saturation ranged from less than 10 percent in bottoms to 45 percent in slope A horizons. Base saturation and cation exchange capacity increased as clay and organic matter increased. Soil moisture distribution in soil profiles and landscapes was related to soil morphology and landtypes respectively. Distribution of citrate-dithionite extractable Fe and Mn in profiles and landtypes was related to measured soil moisture distribution. Stem analysis of forest dominants revealed height growth related to the soil moisture gradient across the landscape. Site index of dominants on uplands and slopes increased down-slope, and yellow-poplar height on bottoms increased with increasing depth to the winter water table. Maximum likelihood factor analysis reduced 32 soil properties to four factors representing A horizon properties, soil texture, subsurface cations, and soil drainage and thickness. The 25 retained soil variables extracted 71 percent of the variance. Discriminant analysis classified all 132 grid observations into correct landtypes, revealing that measured soil properties were related to landtypes. The forest land classification system appears to be a viable method of grouping soils into units suitable for forest management on the Cumberland Plateau
Ask a pathologist
This is a response to the question: I heard there is going to be a shortage of FFP [universal donor type AB plasma] from the American Red Cross during the next few months. What should I do when I need to urgently reverse anticoagulation in patients on warfarin
Caretaker Satisfaction With Law Enforcement Response to Missing Children.
Examines satisfaction with law enforcement from the perspective of all primary caretakers who contacted police when one or more of their children experienced a qualifying episode in the Second National Incidence Studies of Missing, Abducted, Runaway, and Thrownaway Children (NISMART–2) National Household Survey of Adult Caretakers. This Bulletin is the eighth in the NISMART–2 series
Ask a pathologist
QUESTION: I took care of a patient with Disseminated Intravascular Coagulation (DIC), but the pathologist did not see schistocytes on the patient's peripheral blood smear. What is the role of peripheral smear in diagnosing DIC
A study of the Van Orden star
The purpose of the present study was to determine the variations in the star phoric behavior, using the Van Orden Star and a controlled stimulus to accomodation
A max-flow approach to improved lower bounds for quadratic unconstrained binary optimization (QUBO)
AbstractThe “roof dual” of a QUBO (Quadratic Unconstrained Binary Optimization) problem has been introduced in [P.L. Hammer, P. Hansen, B. Simeone, Roof duality, complementation and persistency in quadratic 0–1 optimization, Mathematical Programming 28 (1984) 121–155]; it provides a bound to the optimum value, along with a polynomial test of the sharpness of this bound, and (due to a “persistency” result) it also determines the values of some of the variables at the optimum. In this paper we provide a graph-theoretic approach to provide bounds, which includes as a special case the roof dual bound, and show that these bounds can be computed in O(n3) time by using network flow techniques. We also obtain a decomposition theorem for quadratic pseudo-Boolean functions, improving the persistency result of [P.L. Hammer, P. Hansen, B. Simeone, Roof duality, complementation and persistency in quadratic 0–1 optimization, Mathematical Programming 28 (1984) 121–155]. Finally, we show that the proposed bounds (including roof duality) can be applied in an iterated way to obtain significantly better bounds. Computational experiments on problems up to thousands of variables are presented
The Canada-UK Deep Sub-Millimeter Survey II: First identifications, redshifts and implications for galaxy evolution
Identifications are sought for 12 sub-mm sources detected by Eales et al
(1998). Six are securely identified, two have probable identifications and four
remain unidentified with I_AB > 25. Spectroscopic and estimated photometric
redshifts indicate that four of the sources have z < 1, and four have 1 < z <
3, with the remaining four empty field sources probably lying at z > 3. The
spectral energy distributions of the identifications are consistent with those
of high extinction starbursts such as Arp 220. The far-IR luminosities of the
sources at z > 0.5 are of order 3 x 10^12 h_50^-2 L_sun, i.e. slightly larger
than that of Arp 220. Based on this small sample, the cumulative bolometric
luminosity function shows strong evolution to z ~ 1, but weaker or possibly
even negative evolution beyond. The redshift dependence of the far-IR
luminosity density does not appear, at this early stage, to be inconsistent
with that seen in the ultraviolet luminosity density. Assuming that the energy
source in the far-IR is massive stars, the total luminous output from
star-formation in the Universe is probably dominated by the far-IR emission.
The detected systems have individual star-formation rates (exceeding 300
h_50^-2 M_O yr^-1) that are much higher than seen in the ultraviolet selected
samples, and which are sufficient to form substantial stellar populations on
dynamical timescales of 10^8 yr. The association with merger-like morphologies
and the obvious presence of dust makes it attractive to identify these systems
as forming the metal-rich spheroid population, in which case we would infer
that much of this activity has occurred relatively recently, at z ~ 2.Comment: 17 pages text + 14 figures. Accepted for publication in the
Astrophysical Journal. Gzipped tar file contains one text.ps file for text
and tables, one Fig2.jpg file for Fig 2, and 13 Fig*.ps files for the
remaining figure
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