8,956 research outputs found
Correlations in nuclear energy recurrence relations
The excitation energies of states belonging to the ground state bands of
heavy even-even nuclei are analysed using recurrence relations. Excellent
agreement with experimental data at the 10 keV level is obtained by taking into
account strong correlations which emerge in the analysis. This implies that the
excitation energies can be written as a polynomial of maximum degree four in
the angular momentum.Comment: 4 pages, 1 figure, 1 table, 9 reference
The development of a cislunar space infrastructure
The primary objective of this Advanced Mission Design Program is to define the general characteristics and phased evolution of a near-Earth space infrastructure. The envisioned foundation includes a permanently manned, self-sustaining base on the lunar surface, a space station at the Libration Point between earth and the moon (L1), and a transportation system that anchors these elements to the Low Earth Orbit (LEO) station. The implementation of this conceptual design was carried out with the idea that the infrastructure is an important step in a larger plan to expand man's capabilities in space science and technology. Such expansion depends on low cost, reliable, and frequent access to space for those who wish to use the multiple benefits of this environment. The presence of a cislunar space infrastructure would greatly facilitate the staging of future planetary missions, as well as the full exploration of the lunar potential for science and industry. The rationale for, and a proposed detailed scenario in support of, the cislunar space infrastructure are discussed
Science is perception: what can our sense of smell tell us about ourselves and the world around us?
Human sensory processes are well understood: hearing, seeing, perhaps even tasting and touch—but we do not understand smell—the elusive sense. That is, for the others we know what stimuli causes what response, and why and how. These fundamental questions are not answered within the sphere of smell science; we do not know what it is about a molecule that … smells. I report, here, the status quo theories for olfaction, highlighting what we do not know, and explaining why dismissing the perception of the input as ‘too subjective’ acts as a roadblock not conducive to scientific inquiry. I outline the current and new theory that conjectures a mechanism for signal transduction based on quantum mechanical phenomena, dubbed the ‘swipe card’, which is perhaps controversial but feasible. I show that such lines of thinking may answer some questions, or at least pose the right questions. Most importantly, I draw links and comparisons as to how better understanding of how small (10’s of atoms) molecules can interact so specially with large (10 000’s of atoms) proteins in a way that is so integral to healthy living. Repercussions of this work are not just important in understanding a basic scientific tool used by us all, but often taken for granted, it is also a step closer to understanding generic mechanisms between drug and receptor, for example
Interleukin 2 activation of natural killer cells rapidly induces the expression and phosphorylation of the Leu-23 activation antigen.
IL-2 potentiates both growth and cytotoxic function of T lymphocytes and NK cells. Resting peripheral blood NK cells can respond directly to rIL-2, without requirement for accessory cells or cofactors, and enhanced cytotoxicity can be measured within a few hours after exposure to this lymphokine. In this study, we describe an activation antigen, Leu-23, that is rapidly induced and phosphorylated after IL-2 stimulation of NK cells and a subset of low buoyant density T lymphocytes. Previously, it has been uncertain whether all NK cells or only a subset are responsive to IL-2. Since within 18 h after exposure to IL-2, essentially all NK cells express Leu-23, these findings indicate that all peripheral blood NK cells are responsive to stimulation by IL-2. The Leu-23 antigen is a disulfide-bonded homodimer, composed of 24-kD protein subunits with two N-linked oligosaccharides. Appearance of this glycoprotein on NK cells is IL-2 dependent and closely parallels IL-2-induced cytotoxicity against NK-resistant solid tumor cell targets
Desynchronization of pulse-coupled oscillators with delayed excitatory coupling
Collective behavior of pulse-coupled oscillators has been investigated
widely. As an example of pulse-coupled networks, fireflies display many kinds
of flashing patterns. Mirollo and Strogatz (1990) proposed a pulse-coupled
oscillator model to explain the synchronization of South East Asian fireflies
({\itshape Pteroptyx malaccae}). However, transmission delays were not
considered in their model. In fact, the presence of transmission delays can
lead to desychronization. In this paper, pulse-coupled oscillator networks with
delayed excitatory coupling are studied. Our main result is that under
reasonable assumptions, pulse-coupled oscillator networks with delayed
excitatory coupling can not achieve complete synchronization, which can explain
why another species of fireflies ({\itshape Photinus pyralis}) rarely
synchronizes flashing. Finally, two numerical simulations are given. In the
first simulation, we illustrate that even if all the initial phases are very
close to each other, there could still be big variations in the times to
process the pulses in the pipeline. It implies that asymptotical
synchronization typically also cannot be achieved. In the second simulation, we
exhibit a phenomenon of clustering synchronization
Electromagnetic Transition Strengths in Heavy Nuclei
We calculate reduced B(E2) and B(M1) electromagnetic transition strengths
within and between K-bands in support of a recently proposed model for the
structure of heavy nuclei. Previously, only spectra and a rough indication of
the largest B(E2) strengths were reported. The present more detailed
calculations should aid the experimental identification of the predicted ,
and bands and, in particular, act to confirm or refute the
suggestion that the model and bands correspond to the well known
and widespread beta and gamma bands. Furthermore they pinpoint transitions
which can indicate the presence of a so far elusive band by feeding
relatively strongly into or out of it. Some of these transitions may already
have been measured in Th, Th and U.Comment: 10 pages, 1 Figure, submitted to Physical Review
Dairy and hog farming in northeastern Iowa
On Northeastern Iowa dairy and hog farms, highest returns were obtained where the number of milk cows equaled litters of pigs. This meant about 6 pounds of hogs were produced to each pound of butterfat. Where hog production was less, returns were lower. The butterfat-hog price ratio, during the years of the study, favored hogs, with 1 pound butterfat worth only 3.5 pounds of hogs.
Generally, the strictly dairy herds were more profitable than the dual-purpose herds, even though butterfat prices were unfavorable in comparison to beef, during the period studied. Income from beef in the dual-purpose herds was not enough to offset the lower sales of butterfat.
The dairy herds, with 16.6 cows, averaged 229 pounds butterfat sold or used in the household, and 493 pounds beef per cow, while the dual-purpose herds, with 14.1 cows, averaged 162 pounds butterfat output and 711 pounds beef per cow
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