11,964 research outputs found
Regularly spaced subsums of integer partitions
For integer partitions , where , we study the sum of the parts of odd index. We show
that the average of this sum, over all partitions of , is of the
form More
generally, we study the sum of the parts whose
indices lie in a given arithmetic progression and we show that the average of
this sum, over all partitions of , is of the form
, with explicitly given
constants . Interestingly, for odd and we have
, so in this case the error term is of lower order. The methods used
involve asymptotic formulas for the behavior of Lambert series and the Zeta
function of Hurwitz.
We also show that if is the number of partitions of the sum of
whose parts of even index is , then for every , agrees with a
certain universal sequence, Sloane's sequence \texttt{#A000712}, for
but not for any larger
Studies of the life histories of grass feeding Jassidae
In various papers published in these Bulletins during the past five years attention has been called to the injuries caused in grass land and pastures by the numerous species of Jassidae which swarm, often by millions to the acre, upon various species of grass.
In these papers it has been shown that the loss, though seldom noticed, must be really enormous and that by the use of the tar-pan or “hopper-dozer” the insects may be to a great extent destroyed. Further than this, however, our knowledge has been too meager to furnish a certain basis for remedial measures. It is true studies were made of a few species and some facts learned as to their life-history which warranted the belief that burning, mowing or other methods more satisfactory than the tar-pan might be of service but still so much remained unknown regarding the most common species that there seemed a necessity for a more extensive study. At the beginning of the present season a study was planned, the essential features of which were: 1st, the determination of the life histories of as many as possible of the species known to feed upon grasses; 2nd, the determination of the range of food plants for each species especially in the larval stages and 3rd, the collection of all species occurring on grasses and their careful identification with a close study of the specific limits of each as a basis for further life-history studies
Information sciences experiment system
The rapid expansion of remote sensing capability over the last two decades will take another major leap forward with the advent of the Earth Observing System (Eos). An approach is presented that will permit experiments and demonstrations in onboard information extraction. The approach is a non-intrusive, eavesdropping mode in which a small amount of spacecraft real estate is allocated to an onboard computation resource. How such an approach allows the evaluation of advanced technology in the space environment, advanced techniques in information extraction for both Earth science and information science studies, direct to user data products, and real-time response to events, all without affecting other on-board instrumentation is discussed
Contributions to the Hemipterous Fauna of Iowa
In various papers published during the past five years the senior author has called attention to the injuries caused in grass lands and pastures by the numerous species of Jassidae, which swarm, often by millions to the acre, upon various species of grasses
Signal processing in local neuronal circuits based on activity-dependent noise and competition
We study the characteristics of weak signal detection by a recurrent neuronal
network with plastic synaptic coupling. It is shown that in the presence of an
asynchronous component in synaptic transmission, the network acquires
selectivity with respect to the frequency of weak periodic stimuli. For
non-periodic frequency-modulated stimuli, the response is quantified by the
mutual information between input (signal) and output (network's activity), and
is optimized by synaptic depression. Introducing correlations in signal
structure resulted in the decrease of input-output mutual information. Our
results suggest that in neural systems with plastic connectivity, information
is not merely carried passively by the signal; rather, the information content
of the signal itself might determine the mode of its processing by a local
neuronal circuit.Comment: 15 pages, 4 pages, in press for "Chaos
Cycling of dissolved organic phosphorus compounds in natural waters
U.S. Department of the InteriorU.S. Geological SurveyOpe
Head-on collision of ultrarelativistic charges
We consider the head-on collision of two opposite-charged point particles
moving at the speed of light. Starting from the field of a single charge we
derive in a first step the field generated by uniformly accelerated charge in
the limit of infinite acceleration. From this we then calculate explicitly the
burst of radiation emitted from the head-on collision of two charges and
discuss its distributional structure. The motivation for our investigation
comes from the corresponding gravitational situation where the head-on
collision of two ultrarelativistic particles (black holes) has recently aroused
renewed interest.Comment: 4 figures, uses the AMSmat
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