268 research outputs found
Growth Data from Sections of Acer saccharum
Nine sections of Acer saccharum were cut in 1940, following logging operations on the Albert Smith farm 13 miles southwest of Crawfordsville and about 3 miles east of Alamo, Indiana. Rainfall data were secured from the U.S. Weather Bureau Station which is located at Crawfordsville approximately 13 miles northeast from the forest in which the trees grew. Unfortunately, the rainfall data are not complete from 1884 through 1910; consequently, no growth-rainfall correlation could be determined for those years. Rainfall behavior charts were prepared for the rainfall periods May-August, May-June, May-July, June-July and June-August
The effect of precipitation on annular-ring growth in three species of trees from Brown County, Indiana
The present study is an attempt to determine what rainfall periods show the highest degree of correlation with growth in three species of deciduous trees from Brown County, Indiana, and to determine which area of the tree, i.e., the top or the bottom, gives the closest growth-rainfall correlation.Fuller has shown that there is a close correlation between precipitation for the calendar year in Illinois and increase in diameter in Quercus borealis maxima as shown by thickness of its annual growth rings. Kleine, Potzger, and Friesner, using 11 trees of Quercus alba, 17 of Quecrcus montana, 16 of Quercus velutina, and 9 of Quercus borealis maxima, found a correlation between annual growth and rainfall for the months June, July and August. This work, as in the present study, was done on sites with considerable relief and hence subject to excessive run-off
Inelastic semiclassical Coulomb scattering
We present a semiclassical S-matrix study of inelastic collinear
electron-hydrogen scattering. A simple way to extract all necessary information
from the deflection function alone without having to compute the stability
matrix is described. This includes the determination of the relevant Maslov
indices. Results of singlet and triplet cross sections for excitation and
ionization are reported. The different levels of approximation -- classical,
semiclassical, and uniform semiclassical -- are compared among each other and
to the full quantum result.Comment: 9 figure
Temperatures achieved in human and canine neocortex during intraoperative passive or active focal cooling
Focal cortical cooling inhibits seizures and prevents acquired epileptogenesis in rodents. To investigate the potential clinical utility of this treatment modality, we examined the thermal characteristics of canine and human brain undergoing active and passive surface cooling in intraoperative settings. Four patients with intractable epilepsy were treated in a standard manner. Before the resection of a neocortical epileptogenic focus, multiple intraoperative studies of active (custom-made cooled irrigation-perfused grid) and passive (stainless steel probe) cooling were performed. We also actively cooled the neocortices of two dogs with perfused grids implanted for 2 hours. Focal surface cooling of the human brain causes predictable depth-dependent cooling of the underlying brain tissue. Cooling of 0.6–2°C was achieved both actively and passively to a depth of 10–15 mm from the cortical surface. The perfused grid permitted comparable and persistent cooling of canine neocortex when the craniotomy was closed. Thus, the human cortex can easily be cooled with the use of simple devices such as a cooling grid or a small passive probe. These techniques provide pilot data for the design of a permanently implantable device to control intractable epilepsy
Shape and structure of N=Z 64Ge; Electromagnetic transition rates from the application of the Recoil Distance Method to knock-out reaction
Transition rate measurements are reported for the first and the second 2+
states in N=Z 64Ge. The experimental results are in excellent agreement with
large-scale Shell Model calculations applying the recently developed GXPF1A
interactions. Theoretical analysis suggests that 64Ge is a collective
gamma-soft anharmonic vibrator. The measurement was done using the Recoil
Distance Method (RDM) and a unique combination of state-of-the-art instruments
at the National Superconducting Cyclotron Laboratory (NSCL). States of interest
were populated via an intermediate-energy single-neutron knock-out reaction.
RDM studies of knock-out and fragmentation reaction products hold the promise
of reaching far from stability and providing lifetime information for excited
states in a wide range of nuclei
Superconducting-coil--resistor circuit with electric field quadratic in the current
It is shown for the first time that the observed [Phys. Lett. A 162 (1992)
105] potential difference Phi_t between the resistor and the screen surrounding
the circuit is caused by polarization of the resistor because of the kinetic
energy of the electrons of the superconducting coil. The proportionality of
Phi_t to the square of the current and to the length of the superconducting
wire is explained. It is pointed out that measuring Phi_t makes it possible to
determine the Fermi quasimomentum of the electrons of a metal resistor.Comment: 2 pages, 1 figur
Z=50 shell gap near Sn from intermediate-energy Coulomb excitations in even-mass Sn isotopes
Rare isotope beams of neutron-deficient Sn nuclei from the
fragmentation of Xe were employed in an intermediate-energy Coulomb
excitation experiment yielding transition strengths.
The results indicate that these values are much larger
than predicted by current state-of-the-art shell model calculations. This
discrepancy can be explained if protons from within the Z = 50 shell are
contributing to the structure of low-energy excited states in this region. Such
contributions imply a breaking of the doubly-magic Sn core in the light
Sn isotopes.Comment: 4 pages, 4 figure
Bottom-Up Forcing And The Decline of Steller Sea Lions (Eumetopias jubatus) In Alaska: Assessing The Ocean Climate Hypothesis
Declines of Steller sea lion ( Eumetopias jubatus) populations in the Aleutian Islands and Gulf of Alaska could be a consequence of physical oceanographic changes associated with the 1976–77 climate regime shift. Changes in ocean climate are hypothesized to have affected the quantity, quality, and accessibility of prey, which in turn may have affected the rates of birth and death of sea lions. Recent studies of the spatial and temporal variations in the ocean climate system of the North Pacific support this hypothesis. Ocean climate changes appear to have created adaptive opportunities for various species that are preyed upon by Steller sea lions at mid-trophic levels. The east–west asymmetry of the oceanic response to climate forcing after 1976–77 is consistent with both the temporal aspect (populations decreased after the late 1970s) and the spatial aspect of the decline (western, but not eastern, sea lion populations decreased). These broad-scale climate variations appear to be modulated by regionally sensitive biogeographic structures along the Aleutian Islands and Gulf of Alaska, which include a transition point from coastal to open-ocean conditions at Samalga Pass westward along the Aleutian Islands. These transition points delineate distinct clusterings of different combinations of prey species, which are in turn correlated with differential population sizes and trajectories of Steller sea lions. Archaeological records spanning 4000 yr further indicate that sea lion populations have experienced major shifts in abundance in the past. Shifts in ocean climate are the most parsimonious underlying explanation for the broad suite of ecosystem changes that have been observed in the North Pacific Ocean in recent decades. [ABSTRACT FROM AUTHOR]
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New Skull Material of Taeniolabis taoensis (Multituberculata, Taeniolabididae) from the Early Paleocene (Danian) of the Denver Basin, Colorado
Taeniolabis taoensis is an iconic multituberculate mammal of early Paleocene (Puercan 3) age from the Western Interior of North America. Here we report the discovery of significant new skull material (one nearly complete cranium, two partial crania, one nearly complete dentary) of T. taoensis in phosphatic concretions from the Corral Bluffs study area, Denver Formation (Danian portion), Denver Basin, Colorado. The new skull material provides the first record of the species from the Denver Basin, where the lowest in situ specimen occurs in river channel deposits ~730,000 years after the Cretaceous-Paleogene boundary, roughly coincident with the first appearance of legumes in the basin. The new material, in combination with several previously described and undescribed specimens from the Nacimiento Formation of the San Juan Basin, New Mexico, is the subject of detailed ana- tomical study, aided by micro-computed tomography. Our analyses reveal many previously unknown aspects of skull anatomy. Several regions (e.g., anterior portions of premaxilla, orbit, cranial roof, occiput) preserved in the Corral Bluffs specimens allow considerable revision of previous reconstructions of the external cranial morphology ofT. taoensis. Similarly, anatomical details of the ascending process of the dentary are altered in light of the new material. Although details of internal cranial anatomy (e.g., nasal and endocranial cavities) are difficult to discern in the available specimens, we provide, based on UCMP 98083 and DMNH.EPV 95284, the best evidence to date for inner ear structure in a taeniolabidoid multituberculate. The cochlear canal of T. taoensis is elongate and gently curved and the vestibule is enlarged, although to a lesser degree than in Lambdopsalis
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