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Number of Pages: 12Integrative BiologyGeological Science
The Skylab radar altimeter
A summary of the significant hardware characteristics of the S-193 altimeter experiment portion of the 1973 Skylab Mission is presented. A detailed discussion of the altimetry, oceanographic, and instrumentation technology objectives are presented along with a discussion of the major experiments associated with these objectives
Lab notebooks as scientific communication: investigating development from undergraduate courses to graduate research
In experimental physics, lab notebooks play an essential role in the research
process. For all of the ubiquity of lab notebooks, little formal attention has
been paid to addressing what is considered `best practice' for scientific
documentation and how researchers come to learn these practices in experimental
physics. Using interviews with practicing researchers, namely physics graduate
students, we explore the different experiences researchers had in learning how
to effectively use a notebook for scientific documentation. We find that very
few of those interviewed thought that their undergraduate lab classes
successfully taught them the benefit of maintaining a lab notebook. Most
described training in lab notebook use as either ineffective or outright
missing from their undergraduate lab course experience. Furthermore, a large
majority of those interviewed explained that they did not receive any formal
training in maintaining a lab notebook during their graduate school experience
and received little to no feedback from their advisors on these records. Many
of the interviewees describe learning the purpose of, and how to maintain,
these kinds of lab records only after having a period of trial and error,
having already started doing research in their graduate program. Despite the
central role of scientific documentation in the research enterprise, these
physics graduate students did not gain skills in documentation through formal
instruction, but rather through informal hands-on practice.Comment: 10 page
Experimental breakdown of selected anodized aluminum samples in dilute plasmas
Anodized aluminum samples representative of Space Station Freedom structural material were tested for electrical breakdown under space plasma conditions. In space, this potential arises across the insulating anodized coating when the spacecraft structure is driven to a negative bias relative to the external plasma potential due to plasma-surface interaction phenomena. For anodized materials used in the tests, it was found that breakdown voltage varied from 100 to 2000 volts depending on the sample. The current in the arcs depended on the sample, the capacitor, and the voltage. The level of the arc currents varied from 60 to 1000 amperes. The plasma number density varied from 3 x 10 exp 6 to 10 exp 3 ions per cc. The time between arcs increased as the number density was lowered. Corona testing of anodized samples revealed that samples with higher corona inception voltage had higher arcing inception voltages. From this it is concluded that corona testing may provide a method of screening the samples
Net Gains from 'Net Purchases? Farmers' Preferences for Online and Local Input Purchases
E-commerce represents both threats to and opportunities for rural communities. This study addresses one element of the issue: farmers' willingness to substitute online merchants or national farm input stores for local businesses. Results of a conjoint analysis of contingent choice experiments suggest that farmers are willing to purchase from online or national stores outside their communities if compensated with lower prices or greater services. Results also demonstrate that the context of the input purchase, such as time constraints, was very important not only in valuing these services, but, more broadly, in terms of the farmer's loyalty to a local merchant.e-commerce, farm input purchase, willingness to pay, contingent choice, rural communities, Farm Management, Marketing,
WERE U.S. CROP YIELDS RANDOM IN RECENT YEARS?
Crop Production/Industries,
Instructor perspectives on iteration during upper-division optics lab activities
Although developing proficiency with modeling is a nationally endorsed
learning outcome for upper-division undergraduate physics lab courses, no
corresponding research-based assessments exist. Our longterm goal is to develop
assessments of students' modeling ability that are relevant across multiple
upper-division lab contexts. To this end, we interviewed 19 instructors from 16
institutions about optics lab activities that incorporate photodiodes.
Interviews focused on how those activities were designed to engage students in
some aspects of modeling. We find that, according to many interviewees,
iteration is an important aspect of modeling. In addition, interviewees
described four distinct types of iteration: revising apparatuses, revising
models, revising data-taking procedures, and repeating data collection using
existing apparatuses and procedures. We provide examples of each type of
iteration, and discuss implications for the development of future modeling
assessments.Comment: 4 pages, 1 figure; under revie
Pieri's Formula for Generalized Schur Polynomials
Young's lattice, the lattice of all Young diagrams, has the
Robinson-Schensted-Knuth correspondence, the correspondence between certain
matrices and pairs of semi-standard Young tableaux with the same shape. Fomin
introduced generalized Schur operators to generalize the
Robinson-Schensted-Knuth correspondence. In this sense, generalized Schur
operators are generalizations of semi-standard Young tableaux. We define a
generalization of Schur polynomials as expansion coefficients of generalized
Schur operators. We show that the commutating relation of generalized Schur
operators implies Pieri's formula to generalized Schur polynomials
A density functional theory for general hard-core lattice gases
We put forward a general procedure to obtain an approximate free energy
density functional for any hard-core lattice gas, regardless of the shape of
the particles, the underlying lattice or the dimension of the system. The
procedure is conceptually very simple and recovers effortlessly previous
results for some particular systems. Also, the obtained density functionals
belong to the class of fundamental measure functionals and, therefore, are
always consistent through dimensional reduction. We discuss possible extensions
of this method to account for attractive lattice models.Comment: 4 pages, 1 eps figure, uses RevTeX
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