12,829 research outputs found
Dual Frame (Landline and Cell RDD) Estimation in a National Survey of Latinos
Explores the implications of conducting surveys by both landline and cell phones for issues of survey bias and undercoverage of Latinos, among whom the cell phone-only population is growing. Discusses sampling and weighting methods
Pre-Summit Positioning
Preparations for Wednesday’s state visit by Hu Jintao have been underway for several months. Most of that time was spent negotiating over what deals would be reached, whether there would be a joint statement, and what food would be served. I’m particularly interested to see: 1) Whether Chinese first lady Liu Yongqing will eat the standard fare put on the table as everyone else. She typically travels with her own chef and food; and 2) Whether the American media will get a good photo of the back of Hu Jintao’s head to determine once and for all if he has a bald spot. Chinese media are forbidden to ever shoot him from behind. CNN, please
Planet formation around stars of various masses: Hot super-Earths
We consider trends resulting from two formation mechanisms for short-period
super-Earths: planet-planet scattering and migration. We model scenarios where
these planets originate near the snow line in ``cold finger'' circumstellar
disks. Low-mass planet-planet scattering excites planets to low periastron
orbits only for lower mass stars. With long circularisation times, these
planets reside on long-period eccentric orbits. Closer formation regions mean
planets that reach short-period orbits by migration are most common around
low-mass stars. Above ~1 Solar mass, planets massive enough to migrate to
close-in orbits before the gas disk dissipates are above the critical mass for
gas giant formation. Thus, there is an upper stellar mass limit for
short-period super-Earths that form by migration. If disk masses are
distributed as a power law, planet frequency increases with metallicity because
most disks have low masses. For disk masses distributed around a relatively
high mass, planet frequency decreases with increasing metallicity. As icy
planets migrate, they shepherd interior objects toward the star, which grow to
~1 Earth mass. In contrast to icy migrators, surviving shepherded planets are
rocky. Upon reaching short-period orbits, planets are subject to evaporation
processes. The closest planets may be reduced to rocky or icy cores. Low-mass
stars have lower EUV luminosities, so the level of evaporation decreases with
decreasing stellar mass.Comment: Accepted to ApJ. 13 pages of emulateap
Smart Laboratory Instrument Control Framework
The collection of experimental results in power electronic research requires the coordination of a wide variety of laboratory instrument. Depending on the type of results required, each data point can take a few minutes to collect. This process becomes time consuming when a large number of data points is needed and detracts from long-term research objectives. While there are industry standards that specify communication with these devices, many equipment vendors elect not to follow the standards and use their own protocols for communication. This project provides a framework for developing a smart and connected lab. This includes hardware and software for interacting with all lab instruments while still being simple enough to learn quickly. With minimal training, students can create graphical user interfaces and automation scripts that will greatly simplify interacting with research projects
Who Knew? Refining the Knowability Standard for the Future of Potentially Hazardous Technologies
As consumer technology becomes increasingly complex, so too does the manufacturer’s task in assessing the scope of its duty to warn of potential dangers. A recent decision by the United States Court of Appeals for the Ninth Circuit, Rosa v. Taser International, Inc., offers a prime illustration of this challenge through its analysis of a hazard posed by Taser weaponry. The Rosa court highlights a point of uncertainty in this area of law: courts typically determine which hazards were knowable at the time of manufacture as a matter of law, but they sometimes do so in the absence of a comprehensive standard. This Article evaluates the Ninth Circuit’s approach as a potential model for other courts. After a brief survey of U.S. products liability law pertaining to the “knowability” requirement, this Article analyzes the Rosa decision. Although the Rosa court bemoans the absence of a comprehensive standard for making this determination in California, the court’s reasoning implicitly suggests a three-part test that could serve as a model in California and elsewhere. Such a standard would reduce the legal uncertainty faced by manufacturers assessing the extent of their duty and by plaintiffs assessing the strength of their claims
Protein modelling and associated drug design
PhD ThesisPart one covers an investigation into the secondary and tertiary structure of the protein
Xylanase found in Pseudomonasfluorescens subspecies cellulosa.
Part two documents the Computer Aided Design of Novel Quinazoline Antifolates for
the enzyme Thyrnidylate Synthase.
Partone
Mature Xylanase protein consists of two distinct regions - a cellulose binding domain
and a catalytic region, A and B respectively. Computer modelling of tertiary structure
from primary sequence and secondary turn information proved difficult in the absence
of experimental X-ray crystal data. Consequently,a series of modified proteins bbased on the Xylanase were prepared by Recombinant DNA technology for extraction and
purification. The modified proteins were to be used as a bench mark for quantitative
and definitive calculation and detennination of the secondary structure of the xylanase.
This was to provide an excellent reference point for theoretical modelling of tertiary
structure. Part one of the Thesis documents Computer Modelling work and protein
purification and extraction of the xylanase.
Part two
Thymidylate Synthase (TS) exists as dimer with a single active site in each subunit. It
has been crystallised in two forms; a "reduced" (major), and "oxidised" (minor)
form. The major form of TS contains dUMP covalently bound to cysteine in both
active sites and in the presence of CB3717. One active site of the minor form contains
dUMP non-covalently bound and in the presence of CB3717 while the other active site
contains only inorganic phosphate and CB3717. The active site of TS is a large cavity
that binds CB3717 into two possible confirmations. One is seen in the major form
and one in the minor form.
Part two of my research documents an investigation into enzyme/inhibitor interaction
in TS and covers the Computer Aided Design of a series of inhibitors based on the
knowledge of the TS active site. Several of these compounds have been put forward as
target compounds for synthesis.SERC
Moving Boxes Closer to Home: The Role of SYSCO Corporation in Food System Localization
Increasing demand for local food by foodservice establishments creates new opportunities and challenges for the local food movement. While there is considerable potential for local suppliers to sell more product volume closer to home, the business needs of foodservice establishments may not be compatible with direct marketing approaches that have fueled the growth of the movement. Foodservice establishments typically rely on distributors to provide them with the majority of their food. Drawing on the success of direct marketing, new indirect marketing approaches that link producers and consumers through intermediaries are increasingly advanced within food system localization. The dominance of SYSCO Corporation as an intermediary for foodservice markets has stimulated a dialogue between food system localization actors and this national corporation. New corporate initiatives, such as Buy Local, Sell Fresh, highlight the entry of national corporations into the local food movement. Most of the literature and research on local food systems deals with direct marketing approaches, but there has been little discussion of the role of national foodservice distributors in local food systems, where their inclusion appears potentially contradictory to food system localization. Through in-depth interviews with a SYSCO Corporation official and a telephone survey of SYSCO’s broadline operating companies, this research provides an analysis of this corporation’s current involvement in local food systems, focusing on how factors such as scale, social embeddedness, marketness, and instrumentalism influence these indirect markets. The results indicate that these factors appear as interrelated variables, influencing these markets and the relationships between network actors. While there are exceptions, the benefits of direct marketing which fostered the growth of the local food movement may be absent or marginalized in corporate-mediated foodservice markets. The overall role of SYSCO Corporation in “local” food systems appears to be fairly limited because there is often a conflation of “local” and “regional,” influencing both the procurement activities of SYSCO operating companies and their perspectives on the values associated with “local” food. There is, however, growing support for procurement at a regional level, evidenced through SYSCO’s procurement activities and perspectives which relate to value chains in regional networks
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