117 research outputs found
Studies of respiration rate of dairy bull spermatozoa
Publication authorized October 12, 1942Digitized 2007 AES.Includes bibliographical references (pages 22-24)
An Open Source Software Culture in the Undergraduate Computer Science Curriculum
Open source software has made inroads into mainstream computing where it was once the territory of software altruists, and the open source culture of technological collegiality and accountability may benefit education as well as industry. This paper describes the Recourse project, which seeks to transform the computer science undergraduate curriculum through teaching methods based on open source principles, values, ethics, and tools. Recourse differs from similar projects by bringing the open source culture into the curriculum comprehensively, systematically, and institutionally. The current state of the project is described, and initial results from a pilot exercise are presented
Casimir effect for scalar fields under Robin boundary conditions on plates
We study the Casimir effect for scalar fields with general curvature coupling
subject to mixed boundary conditions at on one () and two () parallel plates at a distance
from each other. Making use of the generalized Abel-Plana
formula previously established by one of the authors \cite{Sahrev}, the Casimir
energy densities are obtained as functions of and of
,,, respectively. In the case of two parallel plates,
a decomposition of the total Casimir energy into volumic and superficial
contributions is provided. The possibility of finding a vanishing energy for
particular parameter choices is shown, and the existence of a minimum to the
surface part is also observed. We show that there is a region in the space of
parameters defining the boundary conditions in which the Casimir forces are
repulsive for small distances and attractive for large distances. This yields
to an interesting possibility for stabilizing the distance between the plates
by using the vacuum forces.Comment: 21 pages, 8 figures, consideration of the contribution from complex
eigenmodes added, possibility for the stabilization of the distance between
the plates is discussed; accepted for publication in J. Phys.
UBVRI Light Curves of 44 Type Ia Supernovae
We present UBVRI photometry of 44 type-Ia supernovae (SN Ia) observed from
1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence
Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The
data set comprises 2190 observations and is the largest homogeneously observed
and reduced sample of SN Ia to date, nearly doubling the number of
well-observed, nearby SN Ia with published multicolor CCD light curves. The
large sample of U-band photometry is a unique addition, with important
connections to SN Ia observed at high redshift. The decline rate of SN Ia
U-band light curves correlates well with the decline rate in other bands, as
does the U-B color at maximum light. However, the U-band peak magnitudes show
an increased dispersion relative to other bands even after accounting for
extinction and decline rate, amounting to an additional ~40% intrinsic scatter
compared to B-band.Comment: 84 authors, 71 pages, 51 tables, 10 figures. Accepted for publication
in the Astronomical Journal. Version with high-res figures and electronic
data at http://astron.berkeley.edu/~saurabh/cfa2snIa
Genetic polymorphisms of the RAS-cytokine pathway and chronic kidney disease
Chronic kidney disease (CKD) in children is irreversible. It is associated with renal failure progression and atherosclerotic cardiovascular (CV) abnormalities. Nearly 60% of children with CKD are affected since birth with congenital or inherited kidney disorders. Preliminary evidence primarily from adult CKD studies indicates common genetic risk factors for CKD and atherosclerotic CV disease. Although multiple physiologic pathways share common genes for CKD and CV disease, substantial evidence supports our attention to the renin angiotensin system (RAS) and the interlinked inflammatory cascade because they modulate the progressions of renal and CV disease. Gene polymorphisms in the RAS-cytokine pathway, through altered gene expression of inflammatory cytokines, are potential factors that modulate the rate of CKD progression and CV abnormalities in patients with CKD. For studying such hypotheses, the cooperative efforts among scientific groups and the availability of robust and affordable technologies to genotype thousands of single nucleotide polymorphisms (SNPs) across the genome make genome-wide association studies an attractive paradigm for studying polygenic diseases such as CKD. Although attractive, such studies should be interpreted carefully, with a fundamental understanding of their potential weaknesses. Nevertheless, whole-genome association studies for diabetic nephropathy and future studies pertaining to other types of CKD will offer further insight for the development of targeted interventions to treat CKD and associated atherosclerotic CV abnormalities in the pediatric CKD population
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
Recommended from our members
INTRACELLULAR DISTRIBUTION OF IRON AND IRON ENZYMES IN CHLOROTIC AND NON-CHLOROTIC TOMATO PLANTS
- …