554 research outputs found
Wind electric plants
The foregoing summary is based on the results from several years’ investigation of and one year’s operation,1 under test, of a wind electric plant located at this Station; and from a study2 of the performance of 66 wind electric plants on Iowa farms. The objective of these investigations was to determine as far as practicable the possibilities and limitations of the wind electric plant under Iowa farmstead conditions.
The origin of the windmill is obscure. There is some evidence that it was first used in Persia during the early centuries of the Christian era.3 It came into prominent use in Europe during the twelfth century. Murphy4 gives a brief sketch of the early history of the windmill in America, and Barbour5 gives a good description of a large variety of homemade mills used in the Middlewest just following pioneer days
The lowa farmer and world war II
World War II is the biggest fact in the Iowa farm situation. Though Iowa is far removed from air bombing and submarine torpedoing, it is on the battle front so far as economic and social effects of the war are concerned. Iowa’s commercial agriculture underwent terrific strain during and following World War I, and the pressures arising out of World War II promise to be similar, although less severe.
It is the purpose of this report to estimate what some of these pressures will be. An understanding of the social and economic forces at work is necessary before plans can be made and action taken to ease the shock of war. The experience of the earlier war helps us to understand these forces, but that experience must be interpreted in light of the changed situation today
Global Ethics and Nanotechnology: A Comparison of the Nanoethics Environments of the EU and China
The following article offers a brief overview of current nanotechnology policy, regulation and ethics in Europe and The People’s Republic of China with the intent of noting (dis)similarities in approach, before focusing on the involvement of the public in science and technology policy (i.e. participatory Technology Assessment). The conclusions of this article are, that (a) in terms of nanosafety as expressed through policy and regulation, China PR and the EU have similar approaches towards, and concerns about, nanotoxicity—the official debate on benefits and risks is not markedly different in the two regions; (b) that there is a similar economic drive behind both regions’ approach to nanodevelopment, the difference being the degree of public concern admitted; and (c) participation in decision-making is fundamentally different in the two regions. Thus in China PR, the focus is on the responsibility of the scientist; in the EU, it is about government accountability to the public. The formulation of a Code of Conduct for scientists in both regions (China PR’s predicted for 2012) reveals both similarity and difference in approach to nanotechnology development. This may change, since individual responsibility alone cannot guide S&T development, and as public participation is increasingly seen globally as integral to governmental decision-making
A Comprehensive Look at LH72 in the Context of Supergiant Shell LMC-4
Stellar spectroscopy, UBV photometry, H imaging, and analysis of data
from the ATCA \ion{H}{1} survey of the LMC are combined in a study of the LMC
OB association LH 72 and its surroundings. LH 72 lies on the rim of a
previously identified \ion{H}{1} shell, SGS-14, and in the interior of LMC-4,
one of the LMC's largest known supergiant shells. Our analysis of the
\ion{H}{1} data finds that SGS-14 is expanding with velocity km
s, giving it an expansion age of 15 Myr. Through the stellar
spectroscopy and photometry, we find similar ages for the oldest stars of LH
72, 30 Myr. We confirm that LH 72 contains an age spread of
30 Myr, similar to the range in ages of stars derived for the entire
surrounding supergiant shell. Combining analysis of the O and B stars with
H imaging of the \ion{H}{2} region DEM 228, we find that DEM 228
accounts for only 60% of the available ionizing Lyman continuum photons.
Comparing the distribution of ionized gas with that of the \ion{H}{1}, we find
that DEM 228 and LH 72 are offset by \sim1-2\arcmin from the peak 21-cm
emission, towards the interior of SGS-14. Taken together, these results imply
that SGS-14 has cleared its interior of gas and triggered the formation of LH
72. On the basis of our results, we suggest that LMC-4 was not formed as unit
but by overlapping shells such as SGS-14, and that LH 72 will evolve to produce
a stellar arc similar to others seen within LMC-4.Comment: 11 pages, 17 figures, uses aastex.cls, Accepted by the Astronomical
Journal, to appear in June 2001 issu
Reakcija β-amino-α,γ-dicianokrotononitrila s acetofenonom: sinteza derivata piridina, piridazina i tiofena s antimikrobnim djelovanjem
Condensation of β-amino-α,γ-dicyanocrotononitrile (1) with acetophenone gave the 2-amino-4-phenylpenta-1,3-diene-1,1,3-tricarbonitrile (2). The latter product was used in a series of heterocyclization reactions when react with different reagents like diazonium salts, hydrazines, hydroxylamine and elemental sulfur to give pyridazine, pyrazole, isoxazole and thiophene derivatives, respectively. On the other hand, it gave pyridine derivatives with aromatic aldehydes followed by reaction with cyanomethylene reagents. The MIC values for the newly synthesized product were measured against E. coli, B. cereus, B. subtilis and C. albicansKondenzacijom β-amino-α,γ-dicijanokrotononitrila 1 s acetofenonom dobiven je 2-amino-4-fenilpenta-1,3-dien-1,1,3-trikarbonitril (2) koji je upotrebljen u reakcijama heterociklizacije s različitim reagensima poput diazonijevih soli, hidrazina, hidroksilamina i elementarnog sumpora pri čemu su nastali derivati piridazina, pirazola, izoksazola, odnosno tiofena. Spoj 2 je u reakciji s aromatskim aldehidima te naknadno sa cijanometilenima dao derivate piridina. Određene su MIC vrijednosti za novosintetizirane spojeve protiv E. coli, B. cereus, B. subtilis i C. albicans
Direct Measurement of the Top Quark Mass at D0
We determine the top quark mass m_t using t-tbar pairs produced in the D0
detector by \sqrt{s} = 1.8 TeV p-pbar collisions in a 125 pb^-1 exposure at the
Fermilab Tevatron. We make a two constraint fit to m_t in t-tbar -> b W^+bbar
W^- final states with one W boson decaying to q-qbar and the other to e-nu or
mu-nu. Likelihood fits to the data yield m_t(l+jets) = 173.3 +- 5.6 (stat) +-
5.5 (syst) GeV/c^2. When this result is combined with an analysis of events in
which both W bosons decay into leptons, we obtain m_t = 172.1 +- 5.2 (stat) +-
4.9 (syst) GeV/c^2. An alternate analysis, using three constraint fits to fixed
top quark masses, gives m_t(l+jets) = 176.0 +- 7.9 (stat) +- 4.8 (syst)
GeV/C^2, consistent with the above result. Studies of kinematic distributions
of the top quark candidates are also presented.Comment: 43 pages, 53 figures, 33 tables. RevTeX. Submitted to Phys. Rev.
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Patterns of variation and covariation in the shapes of mandibular bones of juvenile salmonids in the genus Oncorhynchus
What is the nature of evolutionary divergence of the jaw skeleton within the genus Oncorhynchus? How can two associated bones evolve new shapes and still maintain functional integration? Here, we introduce and test a ‘concordance’ hypothesis, in which an extraordinary matching of the evolutionary shape changes of the dentary and angular articular serves to preserve their fitting together. To test this hypothesis, we examined morphologies of the dentary and angular articular at parr (juvenile) stage, and at three levels of biological organization – between salmon and trout, between sister species within both salmon and trout, and among three types differing in life histories within one species, O. mykiss. The comparisons show bone shape divergences among the groups at each level; morphological divergence between salmon and trout is marked even at this relatively early life history stage. We observed substantial matching between the two mandibular bones in both pattern and amount of shape variation, and in shape covariation across species. These findings strongly support the concordance hypothesis, and reflect functional and/or developmental constraint on morphological evolution. We present evidence for developmental modularity within both bones. The locations of module boundaries were predicted from the patterns of evolutionary divergences, and for the dentary, at least, would appear to facilitate its functional association with the angular articular. The modularity results suggest that development has biased the course of evolution
Probing BFKL Dynamics in the Dijet Cross Section at Large Rapidity Intervals in ppbar Collisions at sqrt{s}=1800 and 630 GeV
Inclusive dijet production at large pseudorapidity intervals (delta_eta)
between the two jets has been suggested as a regime for observing BFKL
dynamics. We have measured the dijet cross section for large delta_eta in ppbar
collisions at sqrt{s}=1800 and 630 GeV using the DO detector. The partonic
cross section increases strongly with the size of delta_eta. The observed
growth is even stronger than expected on the basis of BFKL resummation in the
leading logarithmic approximation. The growth of the partonic cross section can
be accommodated with an effective BFKL intercept of
a_{BFKL}(20GeV)=1.65+/-0.07.Comment: Published in Physical Review Letter
The Azimuthal Decorrelation of Jets Widely Separated in Rapidity
This study reports the first measurement of the azimuthal decorrelation
between jets with pseudorapidity separation up to five units. The data were
accumulated using the D{\O}detector during the 1992--1993 collider run of the
Fermilab Tevatron at 1.8 TeV. These results are compared to
next--to--leading order (NLO) QCD predictions and to two leading--log
approximations (LLA) where the leading--log terms are resummed to all orders in
. The final state jets as predicted by NLO QCD
show less azimuthal decorrelation than the data. The parton showering LLA Monte
Carlo {\small HERWIG} describes the data well; an analytical LLA prediction
based on BFKL resummation shows more decorrelation than the data.Comment: 6 pages with 4 figures, all uuencoded and gzippe
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