287 research outputs found
Research in Economic Education: Five New Initiatives
Research is essential for improvement in teaching and learning economics. William E. Becker et al. (1991) called for new research on the relative merits of multiple-choice and essay tests, on the lasting effects of course work in economics, and on the effects of instructors, instructional techniques, and new technologies on student learning. To respond to the call, the Committee on Economic Education (CEE) of the American Economic Association recruited Robin Bartlett, William Becker, W. Lee Hansen, Peter Kennedy, and the authors to organize a conference that would jump-start new research projects
An experimental survey of the production of alpha decaying heavy elements in the reactions of U +Th at 7.5-6.1 MeV/nucleon
The production of alpha particle decaying heavy nuclei in reactions of
7.5-6.1 MeV/nucleon U +Th has been explored using an in-beam
detection array composed of YAP scintillators and gas ionization chamber-Si
telescopes. Comparisons of alpha energies and half-lives for the observed
products with those of the previously known isotopes and with theoretically
predicted values indicate the observation of a number of previously unreported
alpha emitters. Alpha particle decay energies reaching as high as 12 MeV are
observed. Many of these are expected to be from decay of previously unseen
relatively neutron rich products. While the contributions of isomeric states
require further exploration and specific isotope identifications need to be
made, the production of heavy isotopes with quite high atomic numbers is
suggested by the data.Comment: 12 pages, 12 figure
Spin Dynamics of in the Field-Induced Ordered Phase
- (known as DTN) is a spin-1 material with a strong
single-ion anisotropy that is regarded as a new candidate for Bose-Einstein
condensation (BEC) of spin degrees of freedom. We present a systematic study of
the low-energy excitation spectrum of DTN in the field-induced magnetically
ordered phase by means of high-field electron spin resonance measurements at
temperatures down to 0.45 K. We argue that two gapped modes observed in the
experiment can be consistently interpreted within a four-sublattice
antiferromagnet model with a finite interaction between two tetragonal
subsystems and unbroken axial symmetry. The latter is crucial for the
interpretation of the field-induced ordering in DTN in terms of BEC.Comment: 4 pages, 3 figure
Elements Discrimination in the Study of Super-Heavy Elements using an Ionization Chamber
Dedicated ionization chamber was built and installed to measure the energy
loss of very heavy nuclei at 2.7 MeV/u produced in fusion reactions in inverse
kinematics (beam of 208Pb). After going through the ionization chamber,
products of reactions on 12C, 18O targets are implanted in a Si detector. Their
identification through their alpha decay chain is ambiguous when their
half-life is short. After calibration with Pb and Th nuclei, the ionization
chamber signal allowed us to resolve these ambiguities. In the search for rare
super-heavy nuclei produced in fusion reactions in inverse or symmetric
kinematics, such a chamber will provide direct information on the nuclear
charge of each implanted nucleus.Comment: submitted to NIMA, 10 pages+4 figures, Latex, uses elsart.cls and
grahpic
Site-Dilution in quasi one-dimensional antiferromagnet Sr2(Cu1-xPdx)O3: reduction of Neel Temperature and spatial distribution of ordered moment sizes
We investigate the Neel temperature of Sr2CuO3 as a function of the site
dilution at the Cu (S=1/2) sites with Pd (S=0), utilizing the muon spin
relaxation (muSR) technique. The Neel temperature, which is Tn=5.4K for the
undoped system, becomes significantly reduced for less than one percent of
doping Pd, giving a support for the previous proposal for the good
one-dimensionality. The Pd concentration dependence of the Neel temperature is
compared with a recent theoretical study (S. Eggert, I. Affleck and M.D.P.
Horton, Phys. Rev. Lett. 89, 47202 (2002)) of weakly coupled one-dimensional
antiferromagnetic chains of S=1/2 spins, and a quantitative agreement is found.
The inhomogeneity of the ordered moment sizes is characterized by the muSR time
spectra. We propose a model that the ordered moment size recovers away from the
dopant S=0 sites with a recovery length of \xi = 150-200 sites. The origin of
the finite recovery length \xi for the gapless S=1/2 antiferromagnetic chain is
compared to the estimate based on the effective staggered magnetic field from
the neighboring chains.Comment: 10 pages, 9 figures, submitted to PR
KATANA - a charge-sensitive triggering system for the SRIT experiment
KATANA - the Krakow Array for Triggering with Amplitude discrimiNAtion - has
been built and used as a trigger and veto detector for the SRIT TPC at
RIKEN. Its construction allows operating in magnetic field and providing fast
response for ionizing particles, giving the approximate forward multiplicity
and charge information. Depending on this information, trigger and veto signals
are generated. The article presents performance of the detector and details of
its construction. A simple phenomenological parametrization of the number of
emitted scintillation photons in plastic scintillator is proposed. The effect
of the light output deterioration in the plastic scintillator due to the
in-beam irradiation is discussed.Comment: 14 pages, 11 figure
Spin-Vacancy-Induced Long-Range Order in a New Haldane-Gap Antiferromagnet
Magnetic susceptibility, high-field magnetization and inelastic neutron
scattering experiments are used to study the magnetic properties of a new S=1
quasi-1-dimensional antiferromagnet PbNi2V2O8. Inter-chain interactions are
shown to be almost, but not quite, strong enough to destroy the nonmagnetic
singlet ground state and the energy gap in the magnetic excitation spectrum.
Substituting nonmagnetic Mg (S=0) ions for Ni (S=1) induces a
magnetically ordered state at low temperatures. To our knowledge this is the
first observation of doping-induced long-range order in a Haldane-gap system.Comment: 5 pages including 4 figure
РАННЯ ДІАГНОСТИКА АЛКОГОЛЬНОЇ ЗАЛЕЖНОСТІ В ПРАКТИЦІ СІМЕЙНОГО ЛІКАРЯ
SUMMARY. Early diagnosis of alcohol dependence is one of the most important and urgent problems of modernaddiction narcology. Attraction of family practice doctors to this problem allows them to identify potential cohort ofpersons with symptoms of alcohol dependence. Prompt medical consultation of narcologist will provide an opportunityto confirm or exclude the presence of narcopatology, determine the treatment program. The study involved 255 patientswith hepatic disorders, seeking medical care in somatic hospitals. On the basis of clinical interview, psycho-diagnostictesting, laboratory research complex algorithm designed to identify alcohol dependence in patients with chronic liverdiseases.KEY WORDS: early diagnosis, alcohol abuse, family doctor.РЕЗЮМЕ. Рання діагностика алкогольної залежності є однією з найважливіших і найактуальніших завданьсучасної наркології. Залучення до вирішення цієї проблеми лікарів сімейної практики дозволить на етапіобстеження пацієнтів з гепатопатичною патологією виявити потенційну когорту осіб, які мають симптомиалкогольної залежності. Своєчасна консультація лікаря нарколога дасть можливість підтвердити або виключитинаявність наркопатології, визначити лікувальну програму. Обстежено 255 пацієнтів з гепатопатичними розладами,які звернулися за медичною допомогою в загальносоматичні лікувальні установи. На основі даних клінічногоінтерв'ю, психодіагностичного тестування, лабораторного дослідження розроблено комплексний алгоритмвиявлення алкогольної залежності у пацієнтів з хронічними захворюваннями печінки.КЛЮЧОВІ СЛОВА: рання діагностика, алкогольна залежність, сімейний лікар
Charged particle densities from Au+Au collisions at sqrt{s_{NN}}=130 GeV
We present charged particle densities as a function of pseudorapidity and
collision centrality for the 197Au+197Au reaction at sqrt{s_{NN}}=130 GeV. An
integral charged particle multiplicity of 3860+/-300 is found for the 5% most
central events within the pseudorapidity range -4.7 <= eta <= 4.7. At
mid-rapidity an enhancement in the particle yields per participant nucleon pair
is observed for central events. Near to the beam rapidity, a scaling of the
particle yields consistent with the ``limiting fragmentation'' picture is
observed. Our results are compared to other recent experimental and theoretical
discussions of charged particle densities in ultra-relativistic heavy-ion
collisions.Comment: 14 pages, 4 figures; to be published in Phys. Lett.
A novel experimental setup for rare events selection and its potential application to super-heavy elements search
The paper presents a novel instrumentation for rare events selection which was tested in our research of short-lived super-heavy elements production and detection. The instrumentation includes an active catcher multi-elements system and dedicated electronics. The active catcher located in the forward hemisphere is composed of 63 scintillator detection modules. Reaction products of damped collisions between heavy-ion projectiles and heavy-target nuclei are implanted in the fast plastic scintillators of the active catcher modules. The acquisition system trigger delivered by logical branch of the electronics allows to record the reaction products which decay via the alpha-particle emissions or spontaneous fission which take place between beam bursts. One microsecond wave form signal from FADCs contains information on heavy implanted nucleus as well as its decays
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